[gnus] / texi / gnus.texi

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Copyright @copyright{} 1995--2013 Free Software Foundation, Inc.

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Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with the Front-Cover texts being ``A GNU Manual'',
and with the Back-Cover Texts as in (a) below.  A copy of the license
is included in the section entitled ``GNU Free Documentation License''.

(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
modify this GNU manual.''
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@dircategory Emacs network features
@direntry
* Gnus: (gnus).                 The newsreader Gnus.
@end direntry
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@titlepage
@ifset WEBHACKDEVEL
@title Gnus Manual (DEVELOPMENT VERSION)
@end ifset
@ifclear WEBHACKDEVEL
@title Gnus Manual
@end ifclear

@author by Lars Magne Ingebrigtsen
@page
@vskip 0pt plus 1filll
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@summarycontents
@contents

@node Top
@top The Gnus Newsreader

@ifinfo

You can read news (and mail) from within Emacs by using Gnus.  The news
can be gotten by any nefarious means you can think of---@acronym{NNTP}, local
spool or your mbox file.  All at the same time, if you want to push your
luck.

@c Adjust ../Makefile.in if you change the following line:
This manual corresponds to Ma Gnus v0.8

@ifnottex
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Gnus is the advanced, self-documenting, customizable, extensible
unreal-time newsreader for GNU Emacs.

Oops.  That sounds oddly familiar, so let's start over again to avoid
being accused of plagiarism:

Gnus is a message-reading laboratory.  It will let you look at just
about anything as if it were a newsgroup.  You can read mail with it,
you can browse directories with it, you can @code{ftp} with it---you
can even read news with it!

Gnus tries to empower people who read news the same way Emacs empowers
people who edit text.  Gnus sets no limits to what the user should be
allowed to do.  Users are encouraged to extend Gnus to make it behave
like they want it to behave.  A program should not control people;
people should be empowered to do what they want by using (or abusing)
the program.

@c Adjust ../Makefile.in if you change the following line:
This manual corresponds to Ma Gnus v0.8

@heading Other related manuals
@itemize
@item Message manual: Composing messages
@item Emacs-MIME:     Composing messages; @acronym{MIME}-specific parts.
@item Sieve:          Managing Sieve scripts in Emacs.
@item EasyPG:         @acronym{PGP/MIME} with Gnus.
@item SASL:           @acronym{SASL} authentication in Emacs.
@end itemize

@end iftex

@menu
* Starting Up::              Finding news can be a pain.
* Group Buffer::             Selecting, subscribing and killing groups.
* Summary Buffer::           Reading, saving and posting articles.
* Article Buffer::           Displaying and handling articles.
* Composing Messages::       Information on sending mail and news.
* Select Methods::           Gnus reads all messages from various select methods.
* Scoring::                  Assigning values to articles.
* Searching::                Mail and News search engines.
* Various::                  General purpose settings.
* The End::                  Farewell and goodbye.
* Appendices::               Terminology, Emacs intro, @acronym{FAQ}, History, Internals.
* GNU Free Documentation License:: The license for this documentation.
* Index::                    Variable, function and concept index.
* Key Index::                Key Index.

@c Doesn't work right in html.
@c FIXME Do this in a more standard way.
@ifinfo
Other related manuals

* Message:(message).         Composing messages.
* Emacs-MIME:(emacs-mime).   Composing messages; @acronym{MIME}-specific parts.
* Sieve:(sieve).             Managing Sieve scripts in Emacs.
* EasyPG:(epa).              @acronym{PGP/MIME} with Gnus.
* SASL:(sasl).               @acronym{SASL} authentication in Emacs.
@end ifinfo

@detailmenu
 --- The Detailed Node Listing ---

Starting Gnus

* Finding the News::            Choosing a method for getting news.
* The Server is Down::          How can I read my mail then?
* Slave Gnusae::                You can have more than one Gnus active at a time.
* Fetching a Group::            Starting Gnus just to read a group.
* New Groups::                  What is Gnus supposed to do with new groups?
* Changing Servers::            You may want to move from one server to another.
* Startup Files::               Those pesky startup files---@file{.newsrc}.
* Auto Save::                   Recovering from a crash.
* The Active File::             Reading the active file over a slow line Takes Time.
* Startup Variables::           Other variables you might change.

New Groups

* Checking New Groups::         Determining what groups are new.
* Subscription Methods::        What Gnus should do with new groups.
* Filtering New Groups::        Making Gnus ignore certain new groups.

Group Buffer

* Group Buffer Format::         Information listed and how you can change it.
* Group Maneuvering::           Commands for moving in the group buffer.
* Selecting a Group::           Actually reading news.
* Subscription Commands::       Unsubscribing, killing, subscribing.
* Group Data::                  Changing the info for a group.
* Group Levels::                Levels? What are those, then?
* Group Score::                 A mechanism for finding out what groups you like.
* Marking Groups::              You can mark groups for later processing.
* Foreign Groups::              Creating and editing groups.
* Group Parameters::            Each group may have different parameters set.
* Listing Groups::              Gnus can list various subsets of the groups.
* Sorting Groups::              Re-arrange the group order.
* Group Maintenance::           Maintaining a tidy @file{.newsrc} file.
* Browse Foreign Server::       You can browse a server.  See what it has to offer.
* Exiting Gnus::                Stop reading news and get some work done.
* Group Topics::                A folding group mode divided into topics.
* Non-ASCII Group Names::       Accessing groups of non-English names.
* Misc Group Stuff::            Other stuff that you can to do.

Group Buffer Format

* Group Line Specification::    Deciding how the group buffer is to look.
* Group Mode Line Specification::  The group buffer mode line.
* Group Highlighting::          Having nice colors in the group buffer.

Group Topics

* Topic Commands::              Interactive E-Z commands.
* Topic Variables::             How to customize the topics the Lisp Way.
* Topic Sorting::               Sorting each topic individually.
* Topic Topology::              A map of the world.
* Topic Parameters::            Parameters that apply to all groups in a topic.

Misc Group Stuff

* Scanning New Messages::       Asking Gnus to see whether new messages have arrived.
* Group Information::           Information and help on groups and Gnus.
* Group Timestamp::             Making Gnus keep track of when you last read a group.
* File Commands::               Reading and writing the Gnus files.
* Sieve Commands::              Managing Sieve scripts.

Summary Buffer

* Summary Buffer Format::       Deciding how the summary buffer is to look.
* Summary Maneuvering::         Moving around the summary buffer.
* Choosing Articles::           Reading articles.
* Paging the Article::          Scrolling the current article.
* Reply Followup and Post::     Posting articles.
* Delayed Articles::            Send articles at a later time.
* Marking Articles::            Marking articles as read, expirable, etc.
* Limiting::                    You can limit the summary buffer.
* Threading::                   How threads are made.
* Sorting the Summary Buffer::  How articles and threads are sorted.
* Asynchronous Fetching::       Gnus might be able to pre-fetch articles.
* Article Caching::             You may store articles in a cache.
* Persistent Articles::         Making articles expiry-resistant.
* Sticky Articles::             Article buffers that are not reused.
* Article Backlog::             Having already read articles hang around.
* Saving Articles::             Ways of customizing article saving.
* Decoding Articles::           Gnus can treat series of (uu)encoded articles.
* Article Treatment::           The article buffer can be mangled at will.
* MIME Commands::               Doing MIMEy things with the articles.
* Charsets::                    Character set issues.
* Article Commands::            Doing various things with the article buffer.
* Summary Sorting::             Sorting the summary buffer in various ways.
* Finding the Parent::          No child support? Get the parent.
* Alternative Approaches::      Reading using non-default summaries.
* Tree Display::                A more visual display of threads.
* Mail Group Commands::         Some commands can only be used in mail groups.
* Various Summary Stuff::       What didn't fit anywhere else.
* Exiting the Summary Buffer::  Returning to the Group buffer,
                                or reselecting the current group.
* Crosspost Handling::          How crossposted articles are dealt with.
* Duplicate Suppression::       An alternative when crosspost handling fails.
* Security::                    Decrypt and Verify.
* Mailing List::                Mailing list minor mode.

Summary Buffer Format

* Summary Buffer Lines::        You can specify how summary lines should look.
* To From Newsgroups::          How to not display your own name.
* Summary Buffer Mode Line::    You can say how the mode line should look.
* Summary Highlighting::        Making the summary buffer all pretty and nice.

Choosing Articles

* Choosing Commands::           Commands for choosing articles.
* Choosing Variables::          Variables that influence these commands.

Reply, Followup and Post

* Summary Mail Commands::       Sending mail.
* Summary Post Commands::       Sending news.
* Summary Message Commands::    Other Message-related commands.
* Canceling and Superseding::

Marking Articles

* Unread Articles::             Marks for unread articles.
* Read Articles::               Marks for read articles.
* Other Marks::                 Marks that do not affect readedness.
* Setting Marks::               How to set and remove marks.
* Generic Marking Commands::    How to customize the marking.
* Setting Process Marks::       How to mark articles for later processing.

Threading

* Customizing Threading::       Variables you can change to affect the threading.
* Thread Commands::             Thread based commands in the summary buffer.

Customizing Threading

* Loose Threads::               How Gnus gathers loose threads into bigger threads.
* Filling In Threads::          Making the threads displayed look fuller.
* More Threading::              Even more variables for fiddling with threads.
* Low-Level Threading::         You thought it was over@dots{} but you were wrong!

Decoding Articles

* Uuencoded Articles::          Uudecode articles.
* Shell Archives::              Unshar articles.
* PostScript Files::            Split PostScript.
* Other Files::                 Plain save and binhex.
* Decoding Variables::          Variables for a happy decoding.
* Viewing Files::               You want to look at the result of the decoding?

Decoding Variables

* Rule Variables::              Variables that say how a file is to be viewed.
* Other Decode Variables::      Other decode variables.
* Uuencoding and Posting::      Variables for customizing uuencoding.

Article Treatment

* Article Highlighting::        You want to make the article look like fruit salad.
* Article Fontisizing::         Making emphasized text look nice.
* Article Hiding::              You also want to make certain info go away.
* Article Washing::             Lots of way-neat functions to make life better.
* Article Header::              Doing various header transformations.
* Article Buttons::             Click on URLs, Message-IDs, addresses and the like.
* Article Button Levels::       Controlling appearance of buttons.
* Article Date::                Grumble, UT!
* Article Display::             Display various stuff---X-Face, Picons, Smileys, Gravatars
* Article Signature::           What is a signature?
* Article Miscellanea::         Various other stuff.

Alternative Approaches

* Pick and Read::               First mark articles and then read them.
* Binary Groups::               Auto-decode all articles.

Various Summary Stuff

* Summary Group Information::   Information oriented commands.
* Searching for Articles::      Multiple article commands.
* Summary Generation Commands::
* Really Various Summary Commands::  Those pesky non-conformant commands.

Article Buffer

* Hiding Headers::              Deciding what headers should be displayed.
* Using MIME::                  Pushing articles through @acronym{MIME} before reading them.
* Customizing Articles::        Tailoring the look of the articles.
* Article Keymap::              Keystrokes available in the article buffer.
* Misc Article::                Other stuff.

Composing Messages

* Mail::                        Mailing and replying.
* Posting Server::              What server should you post and mail via?
* POP before SMTP::             You cannot send a mail unless you read a mail.
* Mail and Post::               Mailing and posting at the same time.
* Archived Messages::           Where Gnus stores the messages you've sent.
* Posting Styles::              An easier way to specify who you are.
* Drafts::                      Postponing messages and rejected messages.
* Rejected Articles::           What happens if the server doesn't like your article?
* Signing and encrypting::      How to compose secure messages.

Select Methods

* Server Buffer::               Making and editing virtual servers.
* Getting News::                Reading USENET news with Gnus.
* Using IMAP::                  Reading mail from @acronym{IMAP}.
* Getting Mail::                Reading your personal mail with Gnus.
* Browsing the Web::            Getting messages from a plethora of Web sources.
* Other Sources::               Reading directories, files.
* Combined Groups::             Combining groups into one group.
* Email Based Diary::           Using mails to manage diary events in Gnus.
* Gnus Unplugged::              Reading news and mail offline.

Server Buffer

* Server Buffer Format::        You can customize the look of this buffer.
* Server Commands::             Commands to manipulate servers.
* Example Methods::             Examples server specifications.
* Creating a Virtual Server::   An example session.
* Server Variables::            Which variables to set.
* Servers and Methods::         You can use server names as select methods.
* Unavailable Servers::         Some servers you try to contact may be down.

Getting News

* NNTP::                        Reading news from an @acronym{NNTP} server.
* News Spool::                  Reading news from the local spool.

@acronym{NNTP}

* Direct Functions::            Connecting directly to the server.
* Indirect Functions::          Connecting indirectly to the server.
* Common Variables::            Understood by several connection functions.

Getting Mail

* Mail in a Newsreader::        Important introductory notes.
* Getting Started Reading Mail::  A simple cookbook example.
* Splitting Mail::              How to create mail groups.
* Mail Sources::                How to tell Gnus where to get mail from.
* Mail Back End Variables::     Variables for customizing mail handling.
* Fancy Mail Splitting::        Gnus can do hairy splitting of incoming mail.
* Group Mail Splitting::        Use group customize to drive mail splitting.
* Incorporating Old Mail::      What about the old mail you have?
* Expiring Mail::               Getting rid of unwanted mail.
* Washing Mail::                Removing cruft from the mail you get.
* Duplicates::                  Dealing with duplicated mail.
* Not Reading Mail::            Using mail back ends for reading other files.
* Choosing a Mail Back End::    Gnus can read a variety of mail formats.

Mail Sources

* Mail Source Specifiers::      How to specify what a mail source is.
* Mail Source Customization::   Some variables that influence things.
* Fetching Mail::               Using the mail source specifiers.

Choosing a Mail Back End

* Unix Mail Box::               Using the (quite) standard Un*x mbox.
* Babyl::                       Babyl was used by older versions of Rmail.
* Mail Spool::                  Store your mail in a private spool?
* MH Spool::                    An mhspool-like back end.
* Maildir::                     Another one-file-per-message format.
* Mail Folders::                Having one file for each group.
* Comparing Mail Back Ends::    An in-depth looks at pros and cons.

Browsing the Web

* Archiving Mail::
* Web Searches::                Creating groups from articles that match a string.
* RSS::                         Reading RDF site summary.
* Customizing W3::              Doing stuff to Emacs/W3 from Gnus.

Other Sources

* Directory Groups::            You can read a directory as if it was a newsgroup.
* Anything Groups::             Dired?  Who needs dired?
* Document Groups::             Single files can be the basis of a group.
* Mail-To-News Gateways::       Posting articles via mail-to-news gateways.
* The Empty Backend::           The backend that never has any news.

Document Groups

* Document Server Internals::   How to add your own document types.

Combined Groups

* Virtual Groups::              Combining articles from many groups.

Email Based Diary

* The NNDiary Back End::        Basic setup and usage.
* The Gnus Diary Library::      Utility toolkit on top of nndiary.
* Sending or Not Sending::      A final note on sending diary messages.

The NNDiary Back End

* Diary Messages::              What makes a message valid for nndiary.
* Running NNDiary::             NNDiary has two modes of operation.
* Customizing NNDiary::         Bells and whistles.

The Gnus Diary Library

* Diary Summary Line Format::           A nicer summary buffer line format.
* Diary Articles Sorting::              A nicer way to sort messages.
* Diary Headers Generation::            Not doing it manually.
* Diary Group Parameters::              Not handling them manually.

Gnus Unplugged

* Agent Basics::                How it all is supposed to work.
* Agent Categories::            How to tell the Gnus Agent what to download.
* Agent Commands::              New commands for all the buffers.
* Agent Visuals::               Ways that the agent may effect your summary buffer.
* Agent as Cache::              The Agent is a big cache too.
* Agent Expiry::                How to make old articles go away.
* Agent Regeneration::          How to recover from lost connections and other accidents.
* Agent and flags::             How the Agent maintains flags.
* Agent and IMAP::              How to use the Agent with @acronym{IMAP}.
* Outgoing Messages::           What happens when you post/mail something?
* Agent Variables::             Customizing is fun.
* Example Setup::               An example @file{~/.gnus.el} file for offline people.
* Batching Agents::             How to fetch news from a @code{cron} job.
* Agent Caveats::               What you think it'll do and what it does.

Agent Categories

* Category Syntax::             What a category looks like.
* Category Buffer::             A buffer for maintaining categories.
* Category Variables::          Customize'r'Us.

Agent Commands

* Group Agent Commands::        Configure groups and fetch their contents.
* Summary Agent Commands::      Manually select then fetch specific articles.
* Server Agent Commands::       Select the servers that are supported by the agent.

Scoring

* Summary Score Commands::      Adding score entries for the current group.
* Group Score Commands::        General score commands.
* Score Variables::             Customize your scoring.  (My, what terminology).
* Score File Format::           What a score file may contain.
* Score File Editing::          You can edit score files by hand as well.
* Adaptive Scoring::            Big Sister Gnus knows what you read.
* Home Score File::             How to say where new score entries are to go.
* Followups To Yourself::       Having Gnus notice when people answer you.
* Scoring On Other Headers::    Scoring on non-standard headers.
* Scoring Tips::                How to score effectively.
* Reverse Scoring::             That problem child of old is not problem.
* Global Score Files::          Earth-spanning, ear-splitting score files.
* Kill Files::                  They are still here, but they can be ignored.
* Converting Kill Files::       Translating kill files to score files.
* Advanced Scoring::            Using logical expressions to build score rules.
* Score Decays::                It can be useful to let scores wither away.

Advanced Scoring

* Advanced Scoring Syntax::     A definition.
* Advanced Scoring Examples::   What they look like.
* Advanced Scoring Tips::       Getting the most out of it.

Searching

* nnir::                        Searching with various engines.
* nnmairix::                    Searching with Mairix.

nnir

* What is nnir?::               What does nnir do.
* Basic Usage::                 How to perform simple searches.
* Setting up nnir::             How to set up nnir.

Setting up nnir

* Associating Engines::         How to associate engines.

Various

* Process/Prefix::              A convention used by many treatment commands.
* Interactive::                 Making Gnus ask you many questions.
* Symbolic Prefixes::           How to supply some Gnus functions with options.
* Formatting Variables::        You can specify what buffers should look like.
* Window Layout::               Configuring the Gnus buffer windows.
* Faces and Fonts::             How to change how faces look.
* Mode Lines::                  Displaying information in the mode lines.
* Highlighting and Menus::      Making buffers look all nice and cozy.
* Daemons::                     Gnus can do things behind your back.
* Undo::                        Some actions can be undone.
* Predicate Specifiers::        Specifying predicates.
* Moderation::                  What to do if you're a moderator.
* Image Enhancements::          Modern versions of Emacs/XEmacs can display images.
* Fuzzy Matching::              What's the big fuzz?
* Thwarting Email Spam::        Simple ways to avoid unsolicited commercial email.
* Spam Package::                A package for filtering and processing spam.
* The Gnus Registry::           A package for tracking messages by Message-ID.
* Other modes::                 Interaction with other modes.
* Various Various::             Things that are really various.

Formatting Variables

* Formatting Basics::           A formatting variable is basically a format string.
* Mode Line Formatting::        Some rules about mode line formatting variables.
* Advanced Formatting::         Modifying output in various ways.
* User-Defined Specs::          Having Gnus call your own functions.
* Formatting Fonts::            Making the formatting look colorful and nice.
* Positioning Point::           Moving point to a position after an operation.
* Tabulation::                  Tabulating your output.
* Wide Characters::             Dealing with wide characters.

Image Enhancements

* X-Face::                      Display a funky, teensy black-and-white image.
* Face::                        Display a funkier, teensier colored image.
* Smileys::                     Show all those happy faces the way they were
                                  meant to be shown.
* Picons::                      How to display pictures of what you're reading.
* Gravatars::                   Display the avatar of people you read.
* XVarious::                    Other XEmacsy Gnusey variables.

Thwarting Email Spam

* The problem of spam::         Some background, and some solutions
* Anti-Spam Basics::            Simple steps to reduce the amount of spam.
* SpamAssassin::                How to use external anti-spam tools.
* Hashcash::                    Reduce spam by burning CPU time.

Spam Package

* Spam Package Introduction::
* Filtering Incoming Mail::
* Detecting Spam in Groups::
* Spam and Ham Processors::
* Spam Package Configuration Examples::
* Spam Back Ends::
* Extending the Spam package::
* Spam Statistics Package::

Spam Statistics Package

* Creating a spam-stat dictionary::
* Splitting mail using spam-stat::
* Low-level interface to the spam-stat dictionary::

Appendices

* XEmacs::                      Requirements for installing under XEmacs.
* History::                     How Gnus got where it is today.
* On Writing Manuals::          Why this is not a beginner's guide.
* Terminology::                 We use really difficult, like, words here.
* Customization::               Tailoring Gnus to your needs.
* Troubleshooting::             What you might try if things do not work.
* Gnus Reference Guide::        Rilly, rilly technical stuff.
* Emacs for Heathens::          A short introduction to Emacsian terms.
* Frequently Asked Questions::  The Gnus FAQ

History

* Gnus Versions::               What Gnus versions have been released.
* Why?::                        What's the point of Gnus?
* Compatibility::               Just how compatible is Gnus with @sc{gnus}?
* Conformity::                  Gnus tries to conform to all standards.
* Emacsen::                     Gnus can be run on a few modern Emacsen.
* Gnus Development::            How Gnus is developed.
* Contributors::                Oodles of people.
* New Features::                Pointers to some of the new stuff in Gnus.

New Features

* ding Gnus::                   New things in Gnus 5.0/5.1, the first new Gnus.
* September Gnus::              The Thing Formally Known As Gnus 5.2/5.3.
* Red Gnus::                    Third time best---Gnus 5.4/5.5.
* Quassia Gnus::                Two times two is four, or Gnus 5.6/5.7.
* Pterodactyl Gnus::            Pentad also starts with P, AKA Gnus 5.8/5.9.
* Oort Gnus::                   It's big.  It's far out.  Gnus 5.10/5.11.
* No Gnus::                     Very punny.  Gnus 5.12/5.13
* Ma Gnus::                     Celebrating 25 years of Gnus.

Customization

* Slow/Expensive Connection::   You run a local Emacs and get the news elsewhere.
* Slow Terminal Connection::    You run a remote Emacs.
* Little Disk Space::           You feel that having large setup files is icky.
* Slow Machine::                You feel like buying a faster machine.

Gnus Reference Guide

* Gnus Utility Functions::      Common functions and variable to use.
* Back End Interface::          How Gnus communicates with the servers.
* Score File Syntax::           A BNF definition of the score file standard.
* Headers::                     How Gnus stores headers internally.
* Ranges::                      A handy format for storing mucho numbers.
* Group Info::                  The group info format.
* Extended Interactive::        Symbolic prefixes and stuff.
* Emacs/XEmacs Code::           Gnus can be run under all modern Emacsen.
* Various File Formats::        Formats of files that Gnus use.

Back End Interface

* Required Back End Functions::  Functions that must be implemented.
* Optional Back End Functions::  Functions that need not be implemented.
* Error Messaging::             How to get messages and report errors.
* Writing New Back Ends::       Extending old back ends.
* Hooking New Back Ends Into Gnus::  What has to be done on the Gnus end.
* Mail-like Back Ends::         Some tips on mail back ends.

Various File Formats

* Active File Format::          Information on articles and groups available.
* Newsgroups File Format::      Group descriptions.

Emacs for Heathens

* Keystrokes::                  Entering text and executing commands.
* Emacs Lisp::                  The built-in Emacs programming language.

@end detailmenu
@end menu

@node Starting Up
@chapter Starting Gnus
@cindex starting up

If you haven't used Emacs much before using Gnus, read @ref{Emacs for
Heathens} first.

@kindex M-x gnus
@findex gnus
If your system administrator has set things up properly, starting Gnus
and reading news is extremely easy---you just type @kbd{M-x gnus} in
your Emacs.  If not, you should customize the variable
@code{gnus-select-method} as described in @ref{Finding the News}.  For a
minimal setup for posting should also customize the variables
@code{user-full-name} and @code{user-mail-address}.

@findex gnus-other-frame
@kindex M-x gnus-other-frame
If you want to start Gnus in a different frame, you can use the command
@kbd{M-x gnus-other-frame} instead.

If things do not go smoothly at startup, you have to twiddle some
variables in your @file{~/.gnus.el} file.  This file is similar to
@file{~/.emacs}, but is read when Gnus starts.

If you puzzle at any terms used in this manual, please refer to the
terminology section (@pxref{Terminology}).

@menu
* Finding the News::      Choosing a method for getting news.
* The Server is Down::    How can I read my mail then?
* Slave Gnusae::          You can have more than one Gnus active at a time.
* New Groups::            What is Gnus supposed to do with new groups?
* Changing Servers::      You may want to move from one server to another.
* Startup Files::         Those pesky startup files---@file{.newsrc}.
* Auto Save::             Recovering from a crash.
* The Active File::       Reading the active file over a slow line Takes Time.
* Startup Variables::     Other variables you might change.
@end menu


@node Finding the News
@section Finding the News
@cindex finding news

First of all, you should know that there is a special buffer called
@code{*Server*} that lists all the servers Gnus knows about.  You can
press @kbd{^} from the Group buffer to see it.  In the Server buffer,
you can press @kbd{RET} on a defined server to see all the groups it
serves (subscribed or not!).  You can also add or delete servers, edit
a foreign server's definition, agentize or de-agentize a server, and
do many other neat things.  @xref{Server Buffer}.
@xref{Foreign Groups}.  @xref{Agent Basics}.

@vindex gnus-select-method
@c @head
The @code{gnus-select-method} variable says where Gnus should look for
news.  This variable should be a list where the first element says
@dfn{how} and the second element says @dfn{where}.  This method is your
native method.  All groups not fetched with this method are
secondary or foreign groups.

For instance, if the @samp{news.somewhere.edu} @acronym{NNTP} server is where
you want to get your daily dosage of news from, you'd say:

@lisp
(setq gnus-select-method '(nntp "news.somewhere.edu"))
@end lisp

If you want to read directly from the local spool, say:

@lisp
(setq gnus-select-method '(nnspool ""))
@end lisp

If you can use a local spool, you probably should, as it will almost
certainly be much faster.  But do not use the local spool if your
server is running Leafnode (which is a simple, standalone private news
server); in this case, use @code{(nntp "localhost")}.

@vindex gnus-nntpserver-file
@cindex NNTPSERVER
@cindex @acronym{NNTP} server
If this variable is not set, Gnus will take a look at the
@env{NNTPSERVER} environment variable.  If that variable isn't set,
Gnus will see whether @code{gnus-nntpserver-file}
(@file{/etc/nntpserver} by default) has any opinions on the matter.
If that fails as well, Gnus will try to use the machine running Emacs
as an @acronym{NNTP} server.  That's a long shot, though.

@findex gnus-group-browse-foreign-server
@kindex B (Group)
However, if you use one @acronym{NNTP} server regularly and are just
interested in a couple of groups from a different server, you would be
better served by using the @kbd{B} command in the group buffer.  It will
let you have a look at what groups are available, and you can subscribe
to any of the groups you want to.  This also makes @file{.newsrc}
maintenance much tidier.  @xref{Foreign Groups}.

@vindex gnus-secondary-select-methods
@c @head
A slightly different approach to foreign groups is to set the
@code{gnus-secondary-select-methods} variable.  The select methods
listed in this variable are in many ways just as native as the
@code{gnus-select-method} server.  They will also be queried for active
files during startup (if that's required), and new newsgroups that
appear on these servers will be subscribed (or not) just as native
groups are.

For instance, if you use the @code{nnmbox} back end to read your mail,
you would typically set this variable to

@lisp
(setq gnus-secondary-select-methods '((nnmbox "")))
@end lisp



@node The Server is Down
@section The Server is Down
@cindex server errors

If the default server is down, Gnus will understandably have some
problems starting.  However, if you have some mail groups in addition to
the news groups, you may want to start Gnus anyway.

Gnus, being the trusting sort of program, will ask whether to proceed
without a native select method if that server can't be contacted.  This
will happen whether the server doesn't actually exist (i.e., you have
given the wrong address) or the server has just momentarily taken ill
for some reason or other.  If you decide to continue and have no foreign
groups, you'll find it difficult to actually do anything in the group
buffer.  But, hey, that's your problem.  Blllrph!

@findex gnus-no-server
@kindex M-x gnus-no-server
@c @head
If you know that the server is definitely down, or you just want to read
your mail without bothering with the server at all, you can use the
@code{gnus-no-server} command to start Gnus.  That might come in handy
if you're in a hurry as well.  This command will not attempt to contact
your primary server---instead, it will just activate all groups on level
1 and 2.  (You should preferably keep no native groups on those two
levels.) Also @pxref{Group Levels}.


@node Slave Gnusae
@section Slave Gnusae
@cindex slave

You might want to run more than one Emacs with more than one Gnus at the
same time.  If you are using different @file{.newsrc} files (e.g., if you
are using the two different Gnusae to read from two different servers),
that is no problem whatsoever.  You just do it.

The problem appears when you want to run two Gnusae that use the same
@file{.newsrc} file.

To work around that problem some, we here at the Think-Tank at the Gnus
Towers have come up with a new concept: @dfn{Masters} and
@dfn{slaves}.  (We have applied for a patent on this concept, and have
taken out a copyright on those words.  If you wish to use those words in
conjunction with each other, you have to send $1 per usage instance to
me.  Usage of the patent (@dfn{Master/Slave Relationships In Computer
Applications}) will be much more expensive, of course.)

@findex gnus-slave
Anyway, you start one Gnus up the normal way with @kbd{M-x gnus} (or
however you do it).  Each subsequent slave Gnusae should be started with
@kbd{M-x gnus-slave}.  These slaves won't save normal @file{.newsrc}
files, but instead save @dfn{slave files} that contain information only
on what groups have been read in the slave session.  When a master Gnus
starts, it will read (and delete) these slave files, incorporating all
information from them.  (The slave files will be read in the sequence
they were created, so the latest changes will have precedence.)

Information from the slave files has, of course, precedence over the
information in the normal (i.e., master) @file{.newsrc} file.

If the @file{.newsrc*} files have not been saved in the master when the
slave starts, you may be prompted as to whether to read an auto-save
file.  If you answer ``yes'', the unsaved changes to the master will be
incorporated into the slave.  If you answer ``no'', the slave may see some
messages as unread that have been read in the master.



@node New Groups
@section New Groups
@cindex new groups
@cindex subscription

@vindex gnus-check-new-newsgroups
If you are satisfied that you really never want to see any new groups,
you can set @code{gnus-check-new-newsgroups} to @code{nil}.  This will
also save you some time at startup.  Even if this variable is
@code{nil}, you can always subscribe to the new groups just by pressing
@kbd{U} in the group buffer (@pxref{Group Maintenance}).  This variable
is @code{ask-server} by default.  If you set this variable to
@code{always}, then Gnus will query the back ends for new groups even
when you do the @kbd{g} command (@pxref{Scanning New Messages}).

@menu
* Checking New Groups::         Determining what groups are new.
* Subscription Methods::        What Gnus should do with new groups.
* Filtering New Groups::        Making Gnus ignore certain new groups.
@end menu


@node Checking New Groups
@subsection Checking New Groups

Gnus normally determines whether a group is new or not by comparing
the list of groups from the active file(s) with the lists of
subscribed and dead groups.  This isn't a particularly fast method.
If @code{gnus-check-new-newsgroups} is @code{ask-server}, Gnus will
ask the server for new groups since the last time.  This is both
faster and cheaper.  This also means that you can get rid of the list
of killed groups (@pxref{Group Levels}) altogether, so you may set
@code{gnus-save-killed-list} to @code{nil}, which will save time both
at startup, at exit, and all over.  Saves disk space, too.  Why isn't
this the default, then?  Unfortunately, not all servers support this
command.

I bet I know what you're thinking now: How do I find out whether my
server supports @code{ask-server}?  No?  Good, because I don't have a
fail-safe answer.  I would suggest just setting this variable to
@code{ask-server} and see whether any new groups appear within the next
few days.  If any do, then it works.  If none do, then it doesn't
work.  I could write a function to make Gnus guess whether the server
supports @code{ask-server}, but it would just be a guess.  So I won't.
You could @code{telnet} to the server and say @code{HELP} and see
whether it lists @samp{NEWGROUPS} among the commands it understands.  If
it does, then it might work.  (But there are servers that lists
@samp{NEWGROUPS} without supporting the function properly.)

This variable can also be a list of select methods.  If so, Gnus will
issue an @code{ask-server} command to each of the select methods, and
subscribe them (or not) using the normal methods.  This might be handy
if you are monitoring a few servers for new groups.  A side effect is
that startup will take much longer, so you can meditate while waiting.
Use the mantra ``dingnusdingnusdingnus'' to achieve permanent bliss.


@node Subscription Methods
@subsection Subscription Methods

@vindex gnus-subscribe-newsgroup-method
What Gnus does when it encounters a new group is determined by the
@code{gnus-subscribe-newsgroup-method} variable.

This variable should contain a function.  This function will be called
with the name of the new group as the only parameter.

Some handy pre-fab functions are:

@table @code

@item gnus-subscribe-zombies
@vindex gnus-subscribe-zombies
Make all new groups zombies (@pxref{Group Levels}).  This is the
default.  You can browse the zombies later (with @kbd{A z}) and either
kill them all off properly (with @kbd{S z}), or subscribe to them
(with @kbd{u}).

@item gnus-subscribe-randomly
@vindex gnus-subscribe-randomly
Subscribe all new groups in arbitrary order.  This really means that all
new groups will be added at ``the top'' of the group buffer.

@item gnus-subscribe-alphabetically
@vindex gnus-subscribe-alphabetically
Subscribe all new groups in alphabetical order.

@item gnus-subscribe-hierarchically
@vindex gnus-subscribe-hierarchically
Subscribe all new groups hierarchically.  The difference between this
function and @code{gnus-subscribe-alphabetically} is slight.
@code{gnus-subscribe-alphabetically} will subscribe new groups in a strictly
alphabetical fashion, while this function will enter groups into its
hierarchy.  So if you want to have the @samp{rec} hierarchy before the
@samp{comp} hierarchy, this function will not mess that configuration
up.  Or something like that.

@item gnus-subscribe-interactively
@vindex gnus-subscribe-interactively
Subscribe new groups interactively.  This means that Gnus will ask
you about @strong{all} new groups.  The groups you choose to subscribe
to will be subscribed hierarchically.

@item gnus-subscribe-killed
@vindex gnus-subscribe-killed
Kill all new groups.

@item gnus-subscribe-topics
@vindex gnus-subscribe-topics
Put the groups into the topic that has a matching @code{subscribe} topic
parameter (@pxref{Topic Parameters}).  For instance, a @code{subscribe}
topic parameter that looks like

@example
"nnml"
@end example

will mean that all groups that match that regex will be subscribed under
that topic.

If no topics match the groups, the groups will be subscribed in the
top-level topic.

@end table

@vindex gnus-subscribe-hierarchical-interactive
A closely related variable is
@code{gnus-subscribe-hierarchical-interactive}.  (That's quite a
mouthful.)  If this variable is non-@code{nil}, Gnus will ask you in a
hierarchical fashion whether to subscribe to new groups or not.  Gnus
will ask you for each sub-hierarchy whether you want to descend the
hierarchy or not.

One common mistake is to set the variable a few paragraphs above
(@code{gnus-subscribe-newsgroup-method}) to
@code{gnus-subscribe-hierarchical-interactive}.  This is an error.  This
will not work.  This is ga-ga.  So don't do it.


@node Filtering New Groups
@subsection Filtering New Groups

A nice and portable way to control which new newsgroups should be
subscribed (or ignored) is to put an @dfn{options} line at the start of
the @file{.newsrc} file.  Here's an example:

@example
options -n !alt.all !rec.all sci.all
@end example

@vindex gnus-subscribe-options-newsgroup-method
This line obviously belongs to a serious-minded intellectual scientific
person (or she may just be plain old boring), because it says that all
groups that have names beginning with @samp{alt} and @samp{rec} should
be ignored, and all groups with names beginning with @samp{sci} should
be subscribed.  Gnus will not use the normal subscription method for
subscribing these groups.
@code{gnus-subscribe-options-newsgroup-method} is used instead.  This
variable defaults to @code{gnus-subscribe-alphabetically}.

The ``options -n'' format is very simplistic.  The syntax above is all
that is supports: you can force-subscribe hierarchies, or you can
deny hierarchies, and that's it.

@vindex gnus-options-not-subscribe
@vindex gnus-options-subscribe
If you don't want to mess with your @file{.newsrc} file, you can just
set the two variables @code{gnus-options-subscribe} and
@code{gnus-options-not-subscribe}.  These two variables do exactly the
same as the @file{.newsrc} @samp{options -n} trick.  Both are regexps,
and if the new group matches the former, it will be unconditionally
subscribed, and if it matches the latter, it will be ignored.

@vindex gnus-auto-subscribed-groups
Yet another variable that meddles here is
@code{gnus-auto-subscribed-groups}.  It works exactly like
@code{gnus-options-subscribe}, and is therefore really superfluous,
but I thought it would be nice to have two of these.  This variable is
more meant for setting some ground rules, while the other variable is
used more for user fiddling.  By default this variable makes all new
groups that come from mail back ends (@code{nnml}, @code{nnbabyl},
@code{nnfolder}, @code{nnmbox}, @code{nnmh}, @code{nnimap}, and
@code{nnmaildir}) subscribed.  If you don't like that, just set this
variable to @code{nil}.

@vindex gnus-auto-subscribed-categories
As if that wasn't enough, @code{gnus-auto-subscribed-categories} also
allows you to specify that new groups should be subscribed based on the
category their select methods belong to.  The default is @samp{(mail
post-mail)}, meaning that all new groups from mail-like backends
should be subscribed automatically.

New groups that match these variables are subscribed using
@code{gnus-subscribe-options-newsgroup-method}.


@node Changing Servers
@section Changing Servers
@cindex changing servers

Sometimes it is necessary to move from one @acronym{NNTP} server to another.
This happens very rarely, but perhaps you change jobs, or one server is
very flaky and you want to use another.

Changing the server is pretty easy, right?  You just change
@code{gnus-select-method} to point to the new server?

@emph{Wrong!}

Article numbers are not (in any way) kept synchronized between different
@acronym{NNTP} servers, and the only way Gnus keeps track of what articles
you have read is by keeping track of article numbers.  So when you
change @code{gnus-select-method}, your @file{.newsrc} file becomes
worthless.

@kindex M-x gnus-group-clear-data-on-native-groups
@findex gnus-group-clear-data-on-native-groups
You can use the @kbd{M-x gnus-group-clear-data-on-native-groups}
command to clear out all data that you have on your native groups.
Use with caution.

@kindex M-x gnus-group-clear-data
@findex gnus-group-clear-data
Clear the data from the current group only---nix out marks and the
list of read articles (@code{gnus-group-clear-data}).

After changing servers, you @strong{must} move the cache hierarchy away,
since the cached articles will have wrong article numbers, which will
affect which articles Gnus thinks are read.
@code{gnus-group-clear-data-on-native-groups} will ask you if you want
to have it done automatically; for @code{gnus-group-clear-data}, you
can use @kbd{M-x gnus-cache-move-cache} (but beware, it will move the
cache for all groups).


@node Startup Files
@section Startup Files
@cindex startup files
@cindex .newsrc
@cindex .newsrc.el
@cindex .newsrc.eld

Most common Unix news readers use a shared startup file called
@file{.newsrc}.  This file contains all the information about what
groups are subscribed, and which articles in these groups have been
read.

Things got a bit more complicated with @sc{gnus}.  In addition to
keeping the @file{.newsrc} file updated, it also used a file called
@file{.newsrc.el} for storing all the information that didn't fit into
the @file{.newsrc} file.  (Actually, it also duplicated everything in
the @file{.newsrc} file.)  @sc{gnus} would read whichever one of these
files was the most recently saved, which enabled people to swap between
@sc{gnus} and other newsreaders.

That was kinda silly, so Gnus went one better: In addition to the
@file{.newsrc} and @file{.newsrc.el} files, Gnus also has a file called
@file{.newsrc.eld}.  It will read whichever of these files that are most
recent, but it will never write a @file{.newsrc.el} file.  You should
never delete the @file{.newsrc.eld} file---it contains much information
not stored in the @file{.newsrc} file.

@vindex gnus-save-newsrc-file
@vindex gnus-read-newsrc-file
You can turn off writing the @file{.newsrc} file by setting
@code{gnus-save-newsrc-file} to @code{nil}, which means you can delete
the file and save some space, as well as exiting from Gnus faster.
However, this will make it impossible to use other newsreaders than
Gnus.  But hey, who would want to, right?  Similarly, setting
@code{gnus-read-newsrc-file} to @code{nil} makes Gnus ignore the
@file{.newsrc} file and any @file{.newsrc-SERVER} files, which can be
convenient if you use a different news reader occasionally, and you
want to read a different subset of the available groups with that
news reader.

@vindex gnus-save-killed-list
If @code{gnus-save-killed-list} (default @code{t}) is @code{nil}, Gnus
will not save the list of killed groups to the startup file.  This will
save both time (when starting and quitting) and space (on disk).  It
will also mean that Gnus has no record of what groups are new or old,
so the automatic new groups subscription methods become meaningless.
You should always set @code{gnus-check-new-newsgroups} to @code{nil} or
@code{ask-server} if you set this variable to @code{nil} (@pxref{New
Groups}).  This variable can also be a regular expression.  If that's
the case, remove all groups that do not match this regexp before
saving.  This can be useful in certain obscure situations that involve
several servers where not all servers support @code{ask-server}.

@vindex gnus-startup-file
@vindex gnus-backup-startup-file
@vindex version-control
The @code{gnus-startup-file} variable says where the startup files are.
The default value is @file{~/.newsrc}, with the Gnus (El Dingo) startup
file being whatever that one is, with a @samp{.eld} appended.
If you want to keep multiple numbered backups of this file, set
@code{gnus-backup-startup-file}.  It respects the same values as the
@code{version-control} variable.

@vindex gnus-save-newsrc-hook
@vindex gnus-save-quick-newsrc-hook
@vindex gnus-save-standard-newsrc-hook
@code{gnus-save-newsrc-hook} is called before saving any of the newsrc
files, while @code{gnus-save-quick-newsrc-hook} is called just before
saving the @file{.newsrc.eld} file, and
@code{gnus-save-standard-newsrc-hook} is called just before saving the
@file{.newsrc} file.  The latter two are commonly used to turn version
control on or off.  Version control is on by default when saving the
startup files.  If you want to turn backup creation off, say something like:

@lisp
(defun turn-off-backup ()
  (set (make-local-variable 'backup-inhibited) t))

(add-hook 'gnus-save-quick-newsrc-hook 'turn-off-backup)
(add-hook 'gnus-save-standard-newsrc-hook 'turn-off-backup)
@end lisp

@vindex gnus-init-file
@vindex gnus-site-init-file
When Gnus starts, it will read the @code{gnus-site-init-file}
(@file{.../site-lisp/gnus-init} by default) and @code{gnus-init-file}
(@file{~/.gnus} by default) files.  These are normal Emacs Lisp files
and can be used to avoid cluttering your @file{~/.emacs} and
@file{site-init} files with Gnus stuff.  Gnus will also check for files
with the same names as these, but with @file{.elc} and @file{.el}
suffixes.  In other words, if you have set @code{gnus-init-file} to
@file{~/.gnus}, it will look for @file{~/.gnus.elc}, @file{~/.gnus.el},
and finally @file{~/.gnus} (in this order).  If Emacs was invoked with
the @option{-q} or @option{--no-init-file} options (@pxref{Initial
Options, ,Initial Options, emacs, The Emacs Manual}), Gnus doesn't read
@code{gnus-init-file}.


@node Auto Save
@section Auto Save
@cindex dribble file
@cindex auto-save

Whenever you do something that changes the Gnus data (reading articles,
catching up, killing/subscribing groups), the change is added to a
special @dfn{dribble buffer}.  This buffer is auto-saved the normal
Emacs way.  If your Emacs should crash before you have saved the
@file{.newsrc} files, all changes you have made can be recovered from
this file.

If Gnus detects this file at startup, it will ask the user whether to
read it.  The auto save file is deleted whenever the real startup file is
saved.

@vindex gnus-use-dribble-file
If @code{gnus-use-dribble-file} is @code{nil}, Gnus won't create and
maintain a dribble buffer.  The default is @code{t}.

@vindex gnus-dribble-directory
Gnus will put the dribble file(s) in @code{gnus-dribble-directory}.  If
this variable is @code{nil}, which it is by default, Gnus will dribble
into the directory where the @file{.newsrc} file is located.  (This is
normally the user's home directory.)  The dribble file will get the same
file permissions as the @file{.newsrc} file.

@vindex gnus-always-read-dribble-file
If @code{gnus-always-read-dribble-file} is non-@code{nil}, Gnus will
read the dribble file on startup without querying the user.


@node The Active File
@section The Active File
@cindex active file
@cindex ignored groups

When Gnus starts, or indeed whenever it tries to determine whether new
articles have arrived, it reads the active file.  This is a very large
file that lists all the active groups and articles on the server.

@vindex gnus-ignored-newsgroups
Before examining the active file, Gnus deletes all lines that match the
regexp @code{gnus-ignored-newsgroups}.  This is done primarily to reject
any groups with bogus names, but you can use this variable to make Gnus
ignore hierarchies you aren't ever interested in.  However, this is not
recommended.  In fact, it's highly discouraged.  Instead, @pxref{New
Groups} for an overview of other variables that can be used instead.

@c This variable is
@c @code{nil} by default, and will slow down active file handling somewhat
@c if you set it to anything else.

@vindex gnus-read-active-file
@c @head
The active file can be rather Huge, so if you have a slow network, you
can set @code{gnus-read-active-file} to @code{nil} to prevent Gnus from
reading the active file.  This variable is @code{some} by default.

Gnus will try to make do by getting information just on the groups that
you actually subscribe to.

Note that if you subscribe to lots and lots of groups, setting this
variable to @code{nil} will probably make Gnus slower, not faster.  At
present, having this variable @code{nil} will slow Gnus down
considerably, unless you read news over a 2400 baud modem.

This variable can also have the value @code{some}.  Gnus will then
attempt to read active info only on the subscribed groups.  On some
servers this is quite fast (on sparkling, brand new INN servers that
support the @code{LIST ACTIVE group} command), on others this isn't fast
at all.  In any case, @code{some} should be faster than @code{nil}, and
is certainly faster than @code{t} over slow lines.

Some news servers (old versions of Leafnode and old versions of INN, for
instance) do not support the @code{LIST ACTIVE group}.  For these
servers, @code{nil} is probably the most efficient value for this
variable.

If this variable is @code{nil}, Gnus will ask for group info in total
lock-step, which isn't very fast.  If it is @code{some} and you use an
@acronym{NNTP} server, Gnus will pump out commands as fast as it can, and
read all the replies in one swoop.  This will normally result in better
performance, but if the server does not support the aforementioned
@code{LIST ACTIVE group} command, this isn't very nice to the server.

If you think that starting up Gnus takes too long, try all the three
different values for this variable and see what works best for you.

In any case, if you use @code{some} or @code{nil}, you should definitely
kill all groups that you aren't interested in to speed things up.

Note that this variable also affects active file retrieval from
secondary select methods.


@node Startup Variables
@section Startup Variables

@table @code

@item gnus-load-hook
@vindex gnus-load-hook
A hook run while Gnus is being loaded.  Note that this hook will
normally be run just once in each Emacs session, no matter how many
times you start Gnus.

@item gnus-before-startup-hook
@vindex gnus-before-startup-hook
A hook called as the first thing when Gnus is started.

@item gnus-before-resume-hook
@vindex gnus-before-resume-hook
A hook called as the first thing when Gnus is resumed after a suspend.

@item gnus-startup-hook
@vindex gnus-startup-hook
A hook run as the very last thing after starting up Gnus

@item gnus-started-hook
@vindex gnus-started-hook
A hook that is run as the very last thing after starting up Gnus
successfully.

@item gnus-setup-news-hook
@vindex gnus-setup-news-hook
A hook that is run after reading the @file{.newsrc} file(s), but before
generating the group buffer.

@item gnus-check-bogus-newsgroups
@vindex gnus-check-bogus-newsgroups
If non-@code{nil}, Gnus will check for and delete all bogus groups at
startup.  A @dfn{bogus group} is a group that you have in your
@file{.newsrc} file, but doesn't exist on the news server.  Checking for
bogus groups can take quite a while, so to save time and resources it's
best to leave this option off, and do the checking for bogus groups once
in a while from the group buffer instead (@pxref{Group Maintenance}).

@item gnus-inhibit-startup-message
@vindex gnus-inhibit-startup-message
If non-@code{nil}, the startup message won't be displayed.  That way,
your boss might not notice as easily that you are reading news instead
of doing your job.  Note that this variable is used before
@file{~/.gnus.el} is loaded, so it should be set in @file{.emacs} instead.

@item gnus-no-groups-message
@vindex gnus-no-groups-message
Message displayed by Gnus when no groups are available.

@item gnus-use-backend-marks
@vindex gnus-use-backend-marks
If non-@code{nil}, Gnus will store article marks both in the
@file{.newsrc.eld} file and in the backends.  This will slow down
group operation some.

@end table


@node Group Buffer
@chapter Group Buffer
@cindex group buffer

@c Alex Schroeder suggests to rearrange this as follows:
@c
@c <kensanata> ok, just save it for reference.  I'll go to bed in a minute.
@c   1. Selecting a Group, 2. (new) Finding a Group, 3. Group Levels,
@c   4. Subscription Commands, 5. Group Maneuvering, 6. Group Data,
@c   7. Group Score, 8. Group Buffer Format
@c <kensanata> Group Levels should have more information on levels 5 to 9.  I
@c   suggest to split the 4th paragraph ("Gnus considers groups...") as follows:
@c <kensanata> First, "Gnus considers groups... (default 9)."
@c <kensanata> New, a table summarizing what levels 1 to 9 mean.
@c <kensanata> Third, "Gnus treats subscribed ... reasons of efficiency"
@c <kensanata> Then expand the next paragraph or add some more to it.
@c    This short one sentence explains levels 1 and 2, therefore I understand
@c    that I should keep important news at 3 and boring news at 4.
@c    Say so!  Then go on to explain why I should bother with levels 6 to 9.
@c    Maybe keep those that you don't want to read temporarily at 6,
@c    those that you never want to read at 8, those that offend your
@c    human rights at 9...


The @dfn{group buffer} lists all (or parts) of the available groups.  It
is the first buffer shown when Gnus starts, and will never be killed as
long as Gnus is active.

@iftex
@iflatex
\gnusfigure{The Group Buffer}{320}{
\put(75,50){\epsfig{figure=ps/group,height=9cm}}
\put(120,37){\makebox(0,0)[t]{Buffer name}}
\put(120,38){\vector(1,2){10}}
\put(40,60){\makebox(0,0)[r]{Mode line}}
\put(40,58){\vector(1,0){30}}
\put(200,28){\makebox(0,0)[t]{Native select method}}
\put(200,26){\vector(-1,2){15}}
}
@end iflatex
@end iftex

@menu
* Group Buffer Format::         Information listed and how you can change it.
* Group Maneuvering::           Commands for moving in the group buffer.
* Selecting a Group::           Actually reading news.
* Subscription Commands::       Unsubscribing, killing, subscribing.
* Group Data::                  Changing the info for a group.
* Group Levels::                Levels? What are those, then?
* Group Score::                 A mechanism for finding out what groups you like.
* Marking Groups::              You can mark groups for later processing.
* Foreign Groups::              Creating and editing groups.
* Group Parameters::            Each group may have different parameters set.
* Listing Groups::              Gnus can list various subsets of the groups.
* Sorting Groups::              Re-arrange the group order.
* Group Maintenance::           Maintaining a tidy @file{.newsrc} file.
* Browse Foreign Server::       You can browse a server.  See what it has to offer.
* Exiting Gnus::                Stop reading news and get some work done.
* Group Topics::                A folding group mode divided into topics.
* Non-ASCII Group Names::       Accessing groups of non-English names.
* Misc Group Stuff::            Other stuff that you can to do.
@end menu


@node Group Buffer Format
@section Group Buffer Format

@menu
* Group Line Specification::    Deciding how the group buffer is to look.
* Group Mode Line Specification::  The group buffer mode line.
* Group Highlighting::          Having nice colors in the group buffer.
@end menu

You can customize the Group Mode tool bar, see @kbd{M-x
customize-apropos RET gnus-group-tool-bar}.  This feature is only
available in Emacs.

The tool bar icons are now (de)activated correctly depending on the
cursor position.  Therefore, moving around in the Group Buffer is
slower.  You can disable this via the variable
@code{gnus-group-update-tool-bar}.  Its default value depends on your
Emacs version.

@node Group Line Specification
@subsection Group Line Specification
@cindex group buffer format

The default format of the group buffer is nice and dull, but you can
make it as exciting and ugly as you feel like.

Here's a couple of example group lines:

@example
     25: news.announce.newusers
 *    0: alt.fan.andrea-dworkin
@end example

Quite simple, huh?

You can see that there are 25 unread articles in
@samp{news.announce.newusers}.  There are no unread articles, but some
ticked articles, in @samp{alt.fan.andrea-dworkin} (see that little
asterisk at the beginning of the line?).

@vindex gnus-group-line-format
You can change that format to whatever you want by fiddling with the
@code{gnus-group-line-format} variable.  This variable works along the
lines of a @code{format} specification, which is pretty much the same as
a @code{printf} specifications, for those of you who use (feh!) C@.
@xref{Formatting Variables}.

@samp{%M%S%5y:%B%(%g%)\n} is the value that produced those lines above.

There should always be a colon on the line; the cursor always moves to
the colon after performing an operation.  @xref{Positioning
Point}.  Nothing else is required---not even the group name.  All
displayed text is just window dressing, and is never examined by Gnus.
Gnus stores all real information it needs using text properties.

(Note that if you make a really strange, wonderful, spreadsheet-like
layout, everybody will believe you are hard at work with the accounting
instead of wasting time reading news.)

Here's a list of all available format characters:

@table @samp

@item M
An asterisk if the group only has marked articles.

@item S
Whether the group is subscribed.

@item L
Level of subscribedness.

@item N
Number of unread articles.

@item I
Number of dormant articles.

@item T
Number of ticked articles.

@item R
Number of read articles.

@item U
Number of unseen articles.

@item t
Estimated total number of articles.  (This is really @var{max-number}
minus @var{min-number} plus 1.)

Gnus uses this estimation because the @acronym{NNTP} protocol provides
efficient access to @var{max-number} and @var{min-number} but getting
the true unread message count is not possible efficiently.  For
hysterical raisins, even the mail back ends, where the true number of
unread messages might be available efficiently, use the same limited
interface.  To remove this restriction from Gnus means that the back
end interface has to be changed, which is not an easy job.

The nnml backend (@pxref{Mail Spool}) has a feature called ``group
compaction'' which circumvents this deficiency: the idea is to
renumber all articles from 1, removing all gaps between numbers, hence
getting a correct total count.  Other backends may support this in the
future.  In order to keep your total article count relatively up to
date, you might want to compact your groups (or even directly your
server) from time to time. @xref{Misc Group Stuff}, @xref{Server Commands}.

@item y
Number of unread, unticked, non-dormant articles.

@item i
Number of ticked and dormant articles.

@item g
Full group name.

@item G
Group name.

@item C
Group comment (@pxref{Group Parameters}) or group name if there is no
comment element in the group parameters.

@item D
Newsgroup description.  You need to read the group descriptions
before these will appear, and to do that, you either have to set
@code{gnus-read-active-file} or use the group buffer @kbd{M-d}
command.

@item o
@samp{m} if moderated.

@item O
@samp{(m)} if moderated.

@item s
Select method.

@item B
If the summary buffer for the group is open or not.

@item n
Select from where.

@item z
A string that looks like @samp{<%s:%n>} if a foreign select method is
used.

@item P
Indentation based on the level of the topic (@pxref{Group Topics}).

@item c
@vindex gnus-group-uncollapsed-levels
Short (collapsed) group name.  The @code{gnus-group-uncollapsed-levels}
variable says how many levels to leave at the end of the group name.
The default is 1---this will mean that group names like
@samp{gnu.emacs.gnus} will be shortened to @samp{g.e.gnus}.

@item m
@vindex gnus-new-mail-mark
@cindex %
@samp{%} (@code{gnus-new-mail-mark}) if there has arrived new mail to
the group lately.

@item p
@samp{#} (@code{gnus-process-mark}) if the group is process marked.

@item d
A string that says when you last read the group (@pxref{Group
Timestamp}).

@item F
The disk space used by the articles fetched by both the cache and
agent.  The value is automatically scaled to bytes(B), kilobytes(K),
megabytes(M), or gigabytes(G) to minimize the column width.  A format
of %7F is sufficient for a fixed-width column.

@item u
User defined specifier.  The next character in the format string should
be a letter.  Gnus will call the function
@code{gnus-user-format-function-}@samp{X}, where @samp{X} is the letter
following @samp{%u}.  The function will be passed a single dummy
parameter as argument.  The function should return a string, which will
be inserted into the buffer just like information from any other
specifier.
@end table

@cindex *
All the ``number-of'' specs will be filled with an asterisk (@samp{*})
if no info is available---for instance, if it is a non-activated foreign
group, or a bogus native group.


@node Group Mode Line Specification
@subsection Group Mode Line Specification
@cindex group mode line

@vindex gnus-group-mode-line-format
The mode line can be changed by setting
@code{gnus-group-mode-line-format} (@pxref{Mode Line Formatting}).  It
doesn't understand that many format specifiers:

@table @samp
@item S
The native news server.
@item M
The native select method.
@end table


@node Group Highlighting
@subsection Group Highlighting
@cindex highlighting
@cindex group highlighting

@vindex gnus-group-highlight
Highlighting in the group buffer is controlled by the
@code{gnus-group-highlight} variable.  This is an alist with elements
that look like @code{(@var{form} . @var{face})}.  If @var{form} evaluates to
something non-@code{nil}, the @var{face} will be used on the line.

Here's an example value for this variable that might look nice if the
background is dark:

@lisp
(cond (window-system
       (setq custom-background-mode 'light)
       (defface my-group-face-1
         '((t (:foreground "Red" :bold t))) "First group face")
       (defface my-group-face-2
         '((t (:foreground "DarkSeaGreen4" :bold t)))
         "Second group face")
       (defface my-group-face-3
         '((t (:foreground "Green4" :bold t))) "Third group face")
       (defface my-group-face-4
         '((t (:foreground "SteelBlue" :bold t))) "Fourth group face")
       (defface my-group-face-5
         '((t (:foreground "Blue" :bold t))) "Fifth group face")))

(setq gnus-group-highlight
      '(((> unread 200) . my-group-face-1)
        ((and (< level 3) (zerop unread)) . my-group-face-2)
        ((< level 3) . my-group-face-3)
        ((zerop unread) . my-group-face-4)
        (t . my-group-face-5)))
@end lisp

Also @pxref{Faces and Fonts}.

Variables that are dynamically bound when the forms are evaluated
include:

@table @code
@item group
The group name.
@item unread
The number of unread articles in the group.
@item method
The select method.
@item mailp
Whether the group is a mail group.
@item level
The level of the group.
@item score
The score of the group.
@item ticked
The number of ticked articles in the group.
@item total
The total number of articles in the group.  Or rather,
@var{max-number} minus @var{min-number} plus one.
@item topic
When using the topic minor mode, this variable is bound to the current
topic being inserted.
@end table

When the forms are @code{eval}ed, point is at the beginning of the line
of the group in question, so you can use many of the normal Gnus
functions for snarfing info on the group.

@vindex gnus-group-update-hook
@findex gnus-group-highlight-line
@code{gnus-group-update-hook} is called when a group line is changed.
It will not be called when @code{gnus-visual} is @code{nil}.


@node Group Maneuvering
@section Group Maneuvering
@cindex group movement

All movement commands understand the numeric prefix and will behave as
expected, hopefully.

@table @kbd

@item n
@kindex n (Group)
@findex gnus-group-next-unread-group
Go to the next group that has unread articles
(@code{gnus-group-next-unread-group}).

@item p
@itemx DEL
@kindex DEL (Group)
@kindex p (Group)
@findex gnus-group-prev-unread-group
Go to the previous group that has unread articles
(@code{gnus-group-prev-unread-group}).

@item N
@kindex N (Group)
@findex gnus-group-next-group
Go to the next group (@code{gnus-group-next-group}).

@item P
@kindex P (Group)
@findex gnus-group-prev-group
Go to the previous group (@code{gnus-group-prev-group}).

@item M-n
@kindex M-n (Group)
@findex gnus-group-next-unread-group-same-level
Go to the next unread group on the same (or lower) level
(@code{gnus-group-next-unread-group-same-level}).

@item M-p
@kindex M-p (Group)
@findex gnus-group-prev-unread-group-same-level
Go to the previous unread group on the same (or lower) level
(@code{gnus-group-prev-unread-group-same-level}).
@end table

Three commands for jumping to groups:

@table @kbd

@item j
@kindex j (Group)
@findex gnus-group-jump-to-group
Jump to a group (and make it visible if it isn't already)
(@code{gnus-group-jump-to-group}).  Killed groups can be jumped to, just
like living groups.

@item ,
@kindex , (Group)
@findex gnus-group-best-unread-group
Jump to the unread group with the lowest level
(@code{gnus-group-best-unread-group}).

@item .
@kindex . (Group)
@findex gnus-group-first-unread-group
Jump to the first group with unread articles
(@code{gnus-group-first-unread-group}).
@end table

@vindex gnus-group-goto-unread
If @code{gnus-group-goto-unread} is @code{nil}, all the movement
commands will move to the next group, not the next unread group.  Even
the commands that say they move to the next unread group.  The default
is @code{t}.

@vindex gnus-summary-next-group-on-exit
If @code{gnus-summary-next-group-on-exit} is @code{t}, when a summary is
exited, the point in the group buffer is moved to the next unread group.
Otherwise, the point is set to the group just exited.  The default is
@code{t}.

@node Selecting a Group
@section Selecting a Group
@cindex group selection

@table @kbd

@item SPACE
@kindex SPACE (Group)
@findex gnus-group-read-group
Select the current group, switch to the summary buffer and display the
first unread article (@code{gnus-group-read-group}).  If there are no
unread articles in the group, or if you give a non-numerical prefix to
this command, Gnus will offer to fetch all the old articles in this
group from the server.  If you give a numerical prefix @var{n}, @var{n}
determines the number of articles Gnus will fetch.  If @var{n} is
positive, Gnus fetches the @var{n} newest articles, if @var{n} is
negative, Gnus fetches the @code{abs(@var{n})} oldest articles.

Thus, @kbd{SPC} enters the group normally, @kbd{C-u SPC} offers old
articles, @kbd{C-u 4 2 SPC} fetches the 42 newest articles, and @kbd{C-u
- 4 2 SPC} fetches the 42 oldest ones.

When you are in the group (in the Summary buffer), you can type
@kbd{M-g} to fetch new articles, or @kbd{C-u M-g} to also show the old
ones.

@item RET
@kindex RET (Group)
@findex gnus-group-select-group
Select the current group and switch to the summary buffer
(@code{gnus-group-select-group}).  Takes the same arguments as
@code{gnus-group-read-group}---the only difference is that this command
does not display the first unread article automatically upon group
entry.

@item M-RET
@kindex M-RET (Group)
@findex gnus-group-quick-select-group
This does the same as the command above, but tries to do it with the
minimum amount of fuzz (@code{gnus-group-quick-select-group}).  No
scoring/killing will be performed, there will be no highlights and no
expunging.  This might be useful if you're in a real hurry and have to
enter some humongous group.  If you give a 0 prefix to this command
(i.e., @kbd{0 M-RET}), Gnus won't even generate the summary buffer,
which is useful if you want to toggle threading before generating the
summary buffer (@pxref{Summary Generation Commands}).

@item M-SPACE
@kindex M-SPACE (Group)
@findex gnus-group-visible-select-group
This is yet one more command that does the same as the @kbd{RET}
command, but this one does it without expunging and hiding dormants
(@code{gnus-group-visible-select-group}).

@item C-M-RET
@kindex C-M-RET (Group)
@findex gnus-group-select-group-ephemerally
Finally, this command selects the current group ephemerally without
doing any processing of its contents
(@code{gnus-group-select-group-ephemerally}).  Even threading has been
turned off.  Everything you do in the group after selecting it in this
manner will have no permanent effects.

@end table

@vindex gnus-large-newsgroup
The @code{gnus-large-newsgroup} variable says what Gnus should
consider to be a big group.  If it is @code{nil}, no groups are
considered big.  The default value is 200.  If the group has more
(unread and/or ticked) articles than this, Gnus will query the user
before entering the group.  The user can then specify how many
articles should be fetched from the server.  If the user specifies a
negative number (@var{-n}), the @var{n} oldest articles will be
fetched.  If it is positive, the @var{n} articles that have arrived
most recently will be fetched.

@vindex gnus-large-ephemeral-newsgroup
@code{gnus-large-ephemeral-newsgroup} is the same as
@code{gnus-large-newsgroup}, but is only used for ephemeral
newsgroups.

@vindex gnus-newsgroup-maximum-articles
In groups in some news servers, there might be a big gap between a few
very old articles that will never be expired and the recent ones.  In
such a case, the server will return the data like @code{(1 . 30000000)}
for the @code{LIST ACTIVE group} command, for example.  Even if there
are actually only the articles 1--10 and 29999900--30000000, Gnus doesn't
know it at first and prepares for getting 30000000 articles.  However,
it will consume hundreds megabytes of memories and might make Emacs get
stuck as the case may be.  If you use such news servers, set the
variable @code{gnus-newsgroup-maximum-articles} to a positive number.
The value means that Gnus ignores articles other than this number of the
latest ones in every group.  For instance, the value 10000 makes Gnus
get only the articles 29990001--30000000 (if the latest article number is
30000000 in a group).  Note that setting this variable to a number might
prevent you from reading very old articles.  The default value of the
variable @code{gnus-newsgroup-maximum-articles} is @code{nil}, which
means Gnus never ignores old articles.

@vindex gnus-select-group-hook
@vindex gnus-auto-select-first
@vindex gnus-auto-select-subject
If @code{gnus-auto-select-first} is non-@code{nil}, select an article
automatically when entering a group with the @kbd{SPACE} command.
Which article this is controlled by the
@code{gnus-auto-select-subject} variable.  Valid values for this
variable are:

@table @code

@item unread
Place point on the subject line of the first unread article.

@item first
Place point on the subject line of the first article.

@item unseen
Place point on the subject line of the first unseen article.

@item unseen-or-unread
Place point on the subject line of the first unseen article, and if
there is no such article, place point on the subject line of the first
unread article.

@item best
Place point on the subject line of the highest-scored unread article.

@end table

This variable can also be a function.  In that case, that function
will be called to place point on a subject line.

If you want to prevent automatic selection in some group (say, in a
binary group with Huge articles) you can set the
@code{gnus-auto-select-first} variable to @code{nil} in
@code{gnus-select-group-hook}, which is called when a group is
selected.


@node Subscription Commands
@section Subscription Commands
@cindex subscription

The following commands allow for managing your subscriptions in the
Group buffer.  If you want to subscribe to many groups, it's probably
more convenient to go to the @ref{Server Buffer}, and choose the
server there using @kbd{RET} or @kbd{SPC}.  Then you'll have the
commands listed in @ref{Browse Foreign Server} at hand.

@table @kbd

@item S t
@itemx u
@kindex S t (Group)
@kindex u (Group)
@findex gnus-group-unsubscribe-current-group
@c @icon{gnus-group-unsubscribe}
Toggle subscription to the current group
(@code{gnus-group-unsubscribe-current-group}).

@item S s
@itemx U
@kindex S s (Group)
@kindex U (Group)
@findex gnus-group-unsubscribe-group
Prompt for a group to subscribe, and then subscribe it.  If it was
subscribed already, unsubscribe it instead
(@code{gnus-group-unsubscribe-group}).

@item S k
@itemx C-k
@kindex S k (Group)
@kindex C-k (Group)
@findex gnus-group-kill-group
@c @icon{gnus-group-kill-group}
Kill the current group (@code{gnus-group-kill-group}).

@item S y
@itemx C-y
@kindex S y (Group)
@kindex C-y (Group)
@findex gnus-group-yank-group
Yank the last killed group (@code{gnus-group-yank-group}).

@item C-x C-t
@kindex C-x C-t (Group)
@findex gnus-group-transpose-groups
Transpose two groups (@code{gnus-group-transpose-groups}).  This isn't
really a subscription command, but you can use it instead of a
kill-and-yank sequence sometimes.

@item S w
@itemx C-w
@kindex S w (Group)
@kindex C-w (Group)
@findex gnus-group-kill-region
Kill all groups in the region (@code{gnus-group-kill-region}).

@item S z
@kindex S z (Group)
@findex gnus-group-kill-all-zombies
Kill all zombie groups (@code{gnus-group-kill-all-zombies}).

@item S C-k
@kindex S C-k (Group)
@findex gnus-group-kill-level
Kill all groups on a certain level (@code{gnus-group-kill-level}).
These groups can't be yanked back after killing, so this command should
be used with some caution.  The only time where this command comes in
really handy is when you have a @file{.newsrc} with lots of unsubscribed
groups that you want to get rid off.  @kbd{S C-k} on level 7 will
kill off all unsubscribed groups that do not have message numbers in the
@file{.newsrc} file.

@end table

Also @pxref{Group Levels}.


@node Group Data
@section Group Data

@table @kbd

@item c
@kindex c (Group)
@findex gnus-group-catchup-current
@vindex gnus-group-catchup-group-hook
@c @icon{gnus-group-catchup-current}
Mark all unticked articles in this group as read
(@code{gnus-group-catchup-current}).
@code{gnus-group-catchup-group-hook} is called when catching up a group from
the group buffer.

@item C
@kindex C (Group)
@findex gnus-group-catchup-current-all
Mark all articles in this group, even the ticked ones, as read
(@code{gnus-group-catchup-current-all}).

@item M-c
@kindex M-c (Group)
@findex gnus-group-clear-data
Clear the data from the current group---nix out marks and the list of
read articles (@code{gnus-group-clear-data}).

@item M-x gnus-group-clear-data-on-native-groups
@kindex M-x gnus-group-clear-data-on-native-groups
@findex gnus-group-clear-data-on-native-groups
If you have switched from one @acronym{NNTP} server to another, all your marks
and read ranges have become worthless.  You can use this command to
clear out all data that you have on your native groups.  Use with
caution.

@end table


@node Group Levels
@section Group Levels
@cindex group level
@cindex level

All groups have a level of @dfn{subscribedness}.  For instance, if a
group is on level 2, it is more subscribed than a group on level 5.  You
can ask Gnus to just list groups on a given level or lower
(@pxref{Listing Groups}), or to just check for new articles in groups on
a given level or lower (@pxref{Scanning New Messages}).

Remember:  The higher the level of the group, the less important it is.

@table @kbd

@item S l
@kindex S l (Group)
@findex gnus-group-set-current-level
Set the level of the current group.  If a numeric prefix is given, the
next @var{n} groups will have their levels set.  The user will be
prompted for a level.
@end table

@vindex gnus-level-killed
@vindex gnus-level-zombie
@vindex gnus-level-unsubscribed
@vindex gnus-level-subscribed
Gnus considers groups from levels 1 to
@code{gnus-level-subscribed} (inclusive) (default 5) to be subscribed,
@code{gnus-level-subscribed} (exclusive) and
@code{gnus-level-unsubscribed} (inclusive) (default 7) to be
unsubscribed, @code{gnus-level-zombie} to be zombies (walking dead)
(default 8) and @code{gnus-level-killed} to be killed (completely dead)
(default 9).  Gnus treats subscribed and unsubscribed groups exactly the
same, but zombie and killed groups store no information on what articles
you have read, etc.  This distinction between dead and living
groups isn't done because it is nice or clever, it is done purely for
reasons of efficiency.

It is recommended that you keep all your mail groups (if any) on quite
low levels (e.g., 1 or 2).

Maybe the following description of the default behavior of Gnus helps to
understand what these levels are all about.  By default, Gnus shows you
subscribed nonempty groups, but by hitting @kbd{L} you can have it show
empty subscribed groups and unsubscribed groups, too.  Type @kbd{l} to
go back to showing nonempty subscribed groups again.  Thus, unsubscribed
groups are hidden, in a way.

@cindex zombie groups
Zombie and killed groups are similar to unsubscribed groups in that they
are hidden by default.  But they are different from subscribed and
unsubscribed groups in that Gnus doesn't ask the news server for
information (number of messages, number of unread messages) on zombie
and killed groups.  Normally, you use @kbd{C-k} to kill the groups you
aren't interested in.  If most groups are killed, Gnus is faster.

Why does Gnus distinguish between zombie and killed groups?  Well, when
a new group arrives on the server, Gnus by default makes it a zombie
group.  This means that you are normally not bothered with new groups,
but you can type @kbd{A z} to get a list of all new groups.  Subscribe
the ones you like and kill the ones you don't want.  (@kbd{A k} shows a
list of killed groups.)

If you want to play with the level variables, you should show some care.
Set them once, and don't touch them ever again.  Better yet, don't touch
them at all unless you know exactly what you're doing.

@vindex gnus-level-default-unsubscribed
@vindex gnus-level-default-subscribed
Two closely related variables are @code{gnus-level-default-subscribed}
(default 3) and @code{gnus-level-default-unsubscribed} (default 6),
which are the levels that new groups will be put on if they are
(un)subscribed.  These two variables should, of course, be inside the
relevant valid ranges.

@vindex gnus-keep-same-level
If @code{gnus-keep-same-level} is non-@code{nil}, some movement commands
will only move to groups of the same level (or lower).  In
particular, going from the last article in one group to the next group
will go to the next group of the same level (or lower).  This might be
handy if you want to read the most important groups before you read the
rest.

If this variable is @code{best}, Gnus will make the next newsgroup the
one with the best level.

@vindex gnus-group-default-list-level
All groups with a level less than or equal to
@code{gnus-group-default-list-level} will be listed in the group buffer
by default.
This variable can also be a function.  In that case, that function will
be called and the result will be used as value.


@vindex gnus-group-list-inactive-groups
If @code{gnus-group-list-inactive-groups} is non-@code{nil}, non-active
groups will be listed along with the unread groups.  This variable is
@code{t} by default.  If it is @code{nil}, inactive groups won't be
listed.

@vindex gnus-group-use-permanent-levels
If @code{gnus-group-use-permanent-levels} is non-@code{nil}, once you
give a level prefix to @kbd{g} or @kbd{l}, all subsequent commands will
use this level as the ``work'' level.

@vindex gnus-activate-level
Gnus will normally just activate (i.e., query the server about) groups
on level @code{gnus-activate-level} or less.  If you don't want to
activate unsubscribed groups, for instance, you might set this variable
to 5.  The default is 6.


@node Group Score
@section Group Score
@cindex group score
@cindex group rank
@cindex rank

You would normally keep important groups on high levels, but that scheme
is somewhat restrictive.  Don't you wish you could have Gnus sort the
group buffer according to how often you read groups, perhaps?  Within
reason?

This is what @dfn{group score} is for.  You can have Gnus assign a score
to each group through the mechanism described below.  You can then sort
the group buffer based on this score.  Alternatively, you can sort on
score and then level.  (Taken together, the level and the score is
called the @dfn{rank} of the group.  A group that is on level 4 and has
a score of 1 has a higher rank than a group on level 5 that has a score
of 300.  (The level is the most significant part and the score is the
least significant part.))

@findex gnus-summary-bubble-group
If you want groups you read often to get higher scores than groups you
read seldom you can add the @code{gnus-summary-bubble-group} function to
the @code{gnus-summary-exit-hook} hook.  This will result (after
sorting) in a bubbling sort of action.  If you want to see that in
action after each summary exit, you can add
@code{gnus-group-sort-groups-by-rank} or
@code{gnus-group-sort-groups-by-score} to the same hook, but that will
slow things down somewhat.


@node Marking Groups
@section Marking Groups
@cindex marking groups

If you want to perform some command on several groups, and they appear
subsequently in the group buffer, you would normally just give a
numerical prefix to the command.  Most group commands will then do your
bidding on those groups.

However, if the groups are not in sequential order, you can still
perform a command on several groups.  You simply mark the groups first
with the process mark and then execute the command.

@table @kbd

@item #
@kindex # (Group)
@itemx M m
@kindex M m (Group)
@findex gnus-group-mark-group
Set the mark on the current group (@code{gnus-group-mark-group}).

@item M-#
@kindex M-# (Group)
@itemx M u
@kindex M u (Group)
@findex gnus-group-unmark-group
Remove the mark from the current group
(@code{gnus-group-unmark-group}).

@item M U
@kindex M U (Group)
@findex gnus-group-unmark-all-groups
Remove the mark from all groups (@code{gnus-group-unmark-all-groups}).

@item M w
@kindex M w (Group)
@findex gnus-group-mark-region
Mark all groups between point and mark (@code{gnus-group-mark-region}).

@item M b
@kindex M b (Group)
@findex gnus-group-mark-buffer
Mark all groups in the buffer (@code{gnus-group-mark-buffer}).

@item M r
@kindex M r (Group)
@findex gnus-group-mark-regexp
Mark all groups that match some regular expression
(@code{gnus-group-mark-regexp}).
@end table

Also @pxref{Process/Prefix}.

@findex gnus-group-universal-argument
If you want to execute some command on all groups that have been marked
with the process mark, you can use the @kbd{M-&}
(@code{gnus-group-universal-argument}) command.  It will prompt you for
the command to be executed.


@node Foreign Groups
@section Foreign Groups
@cindex foreign groups

If you recall how to subscribe to servers (@pxref{Finding the News})
you will remember that @code{gnus-secondary-select-methods} and
@code{gnus-select-method} let you write a definition in Emacs Lisp of
what servers you want to see when you start up.  The alternate
approach is to use foreign servers and groups.  ``Foreign'' here means
they are not coming from the select methods.  All foreign server
configuration and subscriptions are stored only in the
@file{~/.newsrc.eld} file.

Below are some group mode commands for making and editing general foreign
groups, as well as commands to ease the creation of a few
special-purpose groups.  All these commands insert the newly created
groups under point---@code{gnus-subscribe-newsgroup-method} is not
consulted.

Changes from the group editing commands are stored in
@file{~/.newsrc.eld} (@code{gnus-startup-file}).  An alternative is the
variable @code{gnus-parameters}, @xref{Group Parameters}.

@table @kbd

@item G m
@kindex G m (Group)
@findex gnus-group-make-group
@cindex making groups
Make a new group (@code{gnus-group-make-group}).  Gnus will prompt you
for a name, a method and possibly an @dfn{address}.  For an easier way
to subscribe to @acronym{NNTP} groups (@pxref{Browse Foreign Server}).

@item G M
@kindex G M (Group)
@findex gnus-group-read-ephemeral-group
Make an ephemeral group (@code{gnus-group-read-ephemeral-group}).  Gnus
will prompt you for a name, a method and an @dfn{address}.

@item G r
@kindex G r (Group)
@findex gnus-group-rename-group
@cindex renaming groups
Rename the current group to something else
(@code{gnus-group-rename-group}).  This is valid only on some
groups---mail groups mostly.  This command might very well be quite slow
on some back ends.

@item G c
@kindex G c (Group)
@cindex customizing
@findex gnus-group-customize
Customize the group parameters (@code{gnus-group-customize}).

@item G e
@kindex G e (Group)
@findex gnus-group-edit-group-method
@cindex renaming groups
Enter a buffer where you can edit the select method of the current
group (@code{gnus-group-edit-group-method}).

@item G p
@kindex G p (Group)
@findex gnus-group-edit-group-parameters
Enter a buffer where you can edit the group parameters
(@code{gnus-group-edit-group-parameters}).

@item G E
@kindex G E (Group)
@findex gnus-group-edit-group
Enter a buffer where you can edit the group info
(@code{gnus-group-edit-group}).

@item G d
@kindex G d (Group)
@findex gnus-group-make-directory-group
@cindex nndir
Make a directory group (@pxref{Directory Groups}).  You will be prompted
for a directory name (@code{gnus-group-make-directory-group}).

@item G h
@kindex G h (Group)
@cindex help group
@findex gnus-group-make-help-group
Make the Gnus help group (@code{gnus-group-make-help-group}).

@item G D
@kindex G D (Group)
@findex gnus-group-enter-directory
@cindex nneething
Read an arbitrary directory as if it were a newsgroup with the
@code{nneething} back end (@code{gnus-group-enter-directory}).
@xref{Anything Groups}.

@item G f
@kindex G f (Group)
@findex gnus-group-make-doc-group
@cindex ClariNet Briefs
@cindex nndoc
Make a group based on some file or other
(@code{gnus-group-make-doc-group}).  If you give a prefix to this
command, you will be prompted for a file name and a file type.
Currently supported types are @code{mbox}, @code{babyl},
@code{digest}, @code{news}, @code{rnews}, @code{mmdf}, @code{forward},
@code{rfc934}, @code{rfc822-forward}, @code{mime-parts},
@code{standard-digest}, @code{slack-digest}, @code{clari-briefs},
@code{nsmail}, @code{outlook}, @code{oe-dbx}, and @code{mailman}.  If
you run this command without a prefix, Gnus will guess at the file
type.  @xref{Document Groups}.

@item G u
@kindex G u (Group)
@vindex gnus-useful-groups
@findex gnus-group-make-useful-group
Create one of the groups mentioned in @code{gnus-useful-groups}
(@code{gnus-group-make-useful-group}).

@item G w
@kindex G w (Group)
@findex gnus-group-make-web-group
@cindex Google
@cindex nnweb
@cindex gmane
Make an ephemeral group based on a web search
(@code{gnus-group-make-web-group}).  If you give a prefix to this
command, make a solid group instead.  You will be prompted for the
search engine type and the search string.  Valid search engine types
include @code{google}, @code{dejanews}, and @code{gmane}.
@xref{Web Searches}.

If you use the @code{google} search engine, you can limit the search
to a particular group by using a match string like
@samp{shaving group:alt.sysadmin.recovery}.

@item G R
@kindex G R (Group)
@findex gnus-group-make-rss-group
Make a group based on an @acronym{RSS} feed
(@code{gnus-group-make-rss-group}).  You will be prompted for an URL@.
@xref{RSS}.

@item G DEL
@kindex G DEL (Group)
@findex gnus-group-delete-group
This function will delete the current group
(@code{gnus-group-delete-group}).  If given a prefix, this function will
actually delete all the articles in the group, and forcibly remove the
group itself from the face of the Earth.  Use a prefix only if you are
absolutely sure of what you are doing.  This command can't be used on
read-only groups (like @code{nntp} groups), though.

@item G V
@kindex G V (Group)
@findex gnus-group-make-empty-virtual
Make a new, fresh, empty @code{nnvirtual} group
(@code{gnus-group-make-empty-virtual}).  @xref{Virtual Groups}.

@item G v
@kindex G v (Group)
@findex gnus-group-add-to-virtual
Add the current group to an @code{nnvirtual} group
(@code{gnus-group-add-to-virtual}).  Uses the process/prefix convention.
@end table

@xref{Select Methods}, for more information on the various select
methods.

@vindex gnus-activate-foreign-newsgroups
If @code{gnus-activate-foreign-newsgroups} is a positive number,
Gnus will check all foreign groups with this level or lower at startup.
This might take quite a while, especially if you subscribe to lots of
groups from different @acronym{NNTP} servers.  Also @pxref{Group Levels};
@code{gnus-activate-level} also affects activation of foreign
newsgroups.


The following commands create ephemeral groups.  They can be called not
only from the Group buffer, but in any Gnus buffer.

@table @code
@item gnus-read-ephemeral-gmane-group
@findex gnus-read-ephemeral-gmane-group
@vindex gnus-gmane-group-download-format
Read an ephemeral group on Gmane.org.  The articles are downloaded via
HTTP using the URL specified by @code{gnus-gmane-group-download-format}.
Gnus will prompt you for a group name, the start article number and an
the article range.

@item gnus-read-ephemeral-gmane-group-url
@findex gnus-read-ephemeral-gmane-group-url
This command is similar to @code{gnus-read-ephemeral-gmane-group}, but
the group name and the article number and range are constructed from a
given @acronym{URL}.  Supported @acronym{URL} formats include:
@indicateurl{http://thread.gmane.org/gmane.foo.bar/12300/focus=12399},
@indicateurl{http://thread.gmane.org/gmane.foo.bar/12345/},
@indicateurl{http://article.gmane.org/gmane.foo.bar/12345/},
@indicateurl{http://permalink.gmane.org/gmane.foo.bar/12345/}, and
@indicateurl{http://news.gmane.org/group/gmane.foo.bar/thread=12345}.

@item gnus-read-ephemeral-emacs-bug-group
@findex gnus-read-ephemeral-emacs-bug-group
Read an Emacs bug report in an ephemeral group.  Gnus will prompt for a
bug number.  The default is the number at point.  The @acronym{URL} is
specified in @code{gnus-bug-group-download-format-alist}.

@item gnus-read-ephemeral-debian-bug-group
@findex gnus-read-ephemeral-debian-bug-group
Read a Debian bug report in an ephemeral group.  Analog to
@code{gnus-read-ephemeral-emacs-bug-group}.
@end table

Some of these command are also useful for article buttons, @xref{Article
Buttons}.

Here is an example:
@lisp
(require 'gnus-art)
(add-to-list
 'gnus-button-alist
 '("#\\([0-9]+\\)\\>" 1
   (string-match "\\<emacs\\>" (or gnus-newsgroup-name ""))
   gnus-read-ephemeral-emacs-bug-group 1))
@end lisp


@node Group Parameters
@section Group Parameters
@cindex group parameters

The group parameters store information local to a particular group.

Use the @kbd{G p} or the @kbd{G c} command to edit group parameters of a
group.  (@kbd{G p} presents you with a Lisp-based interface, @kbd{G c}
presents you with a Customize-like interface.  The latter helps avoid
silly Lisp errors.)  You might also be interested in reading about topic
parameters (@pxref{Topic Parameters}).
Additionally, you can set group parameters via the
@code{gnus-parameters} variable, see below.

Here's an example group parameter list:

@example
((to-address . "ding@@gnus.org")
 (auto-expire . t))
@end example

We see that each element consists of a ``dotted pair''---the thing before
the dot is the key, while the thing after the dot is the value.  All the
parameters have this form @emph{except} local variable specs, which are
not dotted pairs, but proper lists.

Some parameters have correspondent customizable variables, each of which
is an alist of regexps and values.

The following group parameters can be used:

@table @code
@item to-address
@cindex to-address
Address used by when doing followups and new posts.

@example
(to-address . "some@@where.com")
@end example

This is primarily useful in mail groups that represent closed mailing
lists---mailing lists where it's expected that everybody that writes to
the mailing list is subscribed to it.  Since using this parameter
ensures that the mail only goes to the mailing list itself, it means
that members won't receive two copies of your followups.

Using @code{to-address} will actually work whether the group is foreign
or not.  Let's say there's a group on the server that is called
@samp{fa.4ad-l}.  This is a real newsgroup, but the server has gotten
the articles from a mail-to-news gateway.  Posting directly to this
group is therefore impossible---you have to send mail to the mailing
list address instead.

See also @code{gnus-parameter-to-address-alist}.

@item to-list
@cindex to-list
Address used when doing @kbd{a} in that group.

@example
(to-list . "some@@where.com")
@end example

It is totally ignored
when doing a followup---except that if it is present in a news group,
you'll get mail group semantics when doing @kbd{f}.

If you do an @kbd{a} command in a mail group and you have neither a
@code{to-list} group parameter nor a @code{to-address} group parameter,
then a @code{to-list} group parameter will be added automatically upon
sending the message if @code{gnus-add-to-list} is set to @code{t}.
@vindex gnus-add-to-list

@findex gnus-mailing-list-mode
@cindex mail list groups
If this variable is set, @code{gnus-mailing-list-mode} is turned on when
entering summary buffer.

See also @code{gnus-parameter-to-list-alist}.

@anchor{subscribed}
@item subscribed
@cindex subscribed
@cindex Mail-Followup-To
@findex gnus-find-subscribed-addresses
If this parameter is set to @code{t}, Gnus will consider the
to-address and to-list parameters for this group as addresses of
mailing lists you are subscribed to.  Giving Gnus this information is
(only) a first step in getting it to generate correct Mail-Followup-To
headers for your posts to these lists.  The second step is to put the
following in your @file{.gnus.el}

@lisp
(setq message-subscribed-address-functions
      '(gnus-find-subscribed-addresses))
@end lisp

@xref{Mailing Lists, ,Mailing Lists, message, The Message Manual}, for
a complete treatment of available MFT support.

@item visible
@cindex visible
If the group parameter list has the element @code{(visible . t)},
that group will always be visible in the Group buffer, regardless
of whether it has any unread articles.

This parameter cannot be set via @code{gnus-parameters}. See
@code{gnus-permanently-visible-groups} as an alternative.

@item broken-reply-to
@cindex broken-reply-to
Elements like @code{(broken-reply-to . t)} signals that @code{Reply-To}
headers in this group are to be ignored, and for the header to be hidden
if @code{reply-to} is part of @code{gnus-boring-article-headers}.  This
can be useful if you're reading a mailing list group where the listserv
has inserted @code{Reply-To} headers that point back to the listserv
itself.  That is broken behavior.  So there!

@item to-group
@cindex to-group
Elements like @code{(to-group . "some.group.name")} means that all
posts in that group will be sent to @code{some.group.name}.

@item newsgroup
@cindex newsgroup
If you have @code{(newsgroup . t)} in the group parameter list, Gnus
will treat all responses as if they were responses to news articles.
This can be useful if you have a mail group that's really a mirror of a
news group.

@item gcc-self
@cindex gcc-self
If @code{(gcc-self . t)} is present in the group parameter list, newly
composed messages will be @code{Gcc}'d to the current group.  If
@code{(gcc-self . none)} is present, no @code{Gcc:} header will be
generated, if @code{(gcc-self . "string")} is present, this string will
be inserted literally as a @code{gcc} header.  This parameter takes
precedence over any default @code{Gcc} rules as described later
(@pxref{Archived Messages}), with the exception for messages to resend.

@strong{Caveat}: Adding @code{(gcc-self . t)} to the parameter list of
@code{nntp} groups (or the like) isn't valid.  An @code{nntp} server
doesn't accept articles.

@item auto-expire
@cindex auto-expire
@cindex expiring mail
If the group parameter has an element that looks like @code{(auto-expire
. t)}, all articles read will be marked as expirable.  For an
alternative approach, @pxref{Expiring Mail}.

See also @code{gnus-auto-expirable-newsgroups}.

@item total-expire
@cindex total-expire
@cindex expiring mail
If the group parameter has an element that looks like
@code{(total-expire . t)}, all read articles will be put through the
expiry process, even if they are not marked as expirable.  Use with
caution.  Unread, ticked and dormant articles are not eligible for
expiry.

See also @code{gnus-total-expirable-newsgroups}.

@item expiry-wait
@cindex expiry-wait
@vindex nnmail-expiry-wait-function
If the group parameter has an element that looks like
@code{(expiry-wait . 10)}, this value will override any
@code{nnmail-expiry-wait} and @code{nnmail-expiry-wait-function}
(@pxref{Expiring Mail}) when expiring expirable messages.  The value
can either be a number of days (not necessarily an integer) or the
symbols @code{never} or @code{immediate}.

@item expiry-target
@cindex expiry-target
Where expired messages end up.  This parameter overrides
@code{nnmail-expiry-target}.

@item score-file
@cindex score file group parameter
Elements that look like @code{(score-file . "file")} will make
@file{file} into the current score file for the group in question.  All
interactive score entries will be put into this file.

@item adapt-file
@cindex adapt file group parameter
Elements that look like @code{(adapt-file . "file")} will make
@file{file} into the current adaptive file for the group in question.
All adaptive score entries will be put into this file.

@item admin-address
@cindex admin-address
When unsubscribing from a mailing list you should never send the
unsubscription notice to the mailing list itself.  Instead, you'd send
messages to the administrative address.  This parameter allows you to
put the admin address somewhere convenient.

@item display
@cindex display
Elements that look like @code{(display . MODE)} say which articles to
display on entering the group.  Valid values are:

@table @code
@item all
Display all articles, both read and unread.

@item an integer
Display the last @var{integer} articles in the group.  This is the same as
entering the group with @kbd{C-u @var{integer}}.

@item default
Display the default visible articles, which normally includes unread and
ticked articles.

@item an array
Display articles that satisfy a predicate.

Here are some examples:

@table @code
@item [unread]
Display only unread articles.

@item [not expire]
Display everything except expirable articles.

@item [and (not reply) (not expire)]
Display everything except expirable and articles you've already
responded to.
@end table

The available operators are @code{not}, @code{and} and @code{or}.
Predicates include @code{tick}, @code{unsend}, @code{undownload},
@code{unread}, @code{dormant}, @code{expire}, @code{reply},
@code{killed}, @code{bookmark}, @code{score}, @code{save},
@code{cache}, @code{forward}, and @code{unseen}.

@end table

The @code{display} parameter works by limiting the summary buffer to
the subset specified.  You can pop the limit by using the @kbd{/ w}
command (@pxref{Limiting}).

@item comment
@cindex comment
Elements that look like @code{(comment . "This is a comment")} are
arbitrary comments on the group.  You can display comments in the
group line (@pxref{Group Line Specification}).

@item charset
@cindex charset
Elements that look like @code{(charset . iso-8859-1)} will make
@code{iso-8859-1} the default charset; that is, the charset that will be
used for all articles that do not specify a charset.

See also @code{gnus-group-charset-alist}.

@item ignored-charsets
@cindex ignored-charset
Elements that look like @code{(ignored-charsets x-unknown iso-8859-1)}
will make @code{iso-8859-1} and @code{x-unknown} ignored; that is, the
default charset will be used for decoding articles.

See also @code{gnus-group-ignored-charsets-alist}.

@item posting-style
@cindex posting-style
You can store additional posting style information for this group
here (@pxref{Posting Styles}).  The format is that of an entry in the
@code{gnus-posting-styles} alist, except that there's no regexp matching
the group name (of course).  Style elements in this group parameter will
take precedence over the ones found in @code{gnus-posting-styles}.

For instance, if you want a funky name and signature in this group only,
instead of hacking @code{gnus-posting-styles}, you could put something
like this in the group parameters:

@example
(posting-style
  (name "Funky Name")
  ("X-Message-SMTP-Method" "smtp smtp.example.org 587")
  ("X-My-Header" "Funky Value")
  (signature "Funky Signature"))
@end example

If you're using topics to organize your group buffer
(@pxref{Group Topics}), note that posting styles can also be set in
the topics parameters. Posting styles in topic parameters apply to all
groups in this topic. More precisely, the posting-style settings for a
group result from the hierarchical merging of all posting-style
entries in the parameters of this group and all the topics it belongs
to.


@item post-method
@cindex post-method
If it is set, the value is used as the method for posting message
instead of @code{gnus-post-method}.

@item mail-source
@cindex mail-source
If it is set, and the setting of @code{mail-sources} includes a
@code{group} mail source (@pxref{Mail Sources}), the value is a
mail source for this group.

@item banner
@cindex banner
An item like @code{(banner . @var{regexp})} causes any part of an article
that matches the regular expression @var{regexp} to be stripped.  Instead of
@var{regexp}, you can also use the symbol @code{signature} which strips the
last signature or any of the elements of the alist
@code{gnus-article-banner-alist}.

@item sieve
@cindex sieve
This parameter contains a Sieve test that should match incoming mail
that should be placed in this group.  From this group parameter, a
Sieve @samp{IF} control structure is generated, having the test as the
condition and @samp{fileinto "group.name";} as the body.

For example, if the @samp{INBOX.list.sieve} group has the @code{(sieve
address "sender" "sieve-admin@@extundo.com")} group parameter, when
translating the group parameter into a Sieve script (@pxref{Sieve
Commands}) the following Sieve code is generated:

@example
if address "sender" "sieve-admin@@extundo.com" @{
        fileinto "INBOX.list.sieve";
@}
@end example

To generate tests for multiple email-addresses use a group parameter
like @code{(sieve address "sender" ("name@@one.org" else@@two.org"))}.
When generating a sieve script (@pxref{Sieve Commands}) Sieve code
like the following is generated:

@example
if address "sender" ["name@@one.org", "else@@two.org"] @{
        fileinto "INBOX.list.sieve";
@}
@end example

You can also use regexp expansions in the rules:

@example
(sieve header :regex "list-id" "<c++std-\\1.accu.org>")
@end example

See @pxref{Sieve Commands} for commands and variables that might be of
interest in relation to the sieve parameter.

The Sieve language is described in RFC 3028.  @xref{Top, Emacs Sieve,
Top, sieve, Emacs Sieve}.

@item (agent parameters)
If the agent has been enabled, you can set any of its parameters to
control the behavior of the agent in individual groups.  See Agent
Parameters in @ref{Category Syntax}.  Most users will choose to set
agent parameters in either an agent category or group topic to
minimize the configuration effort.

@item (@var{variable} @var{form})
You can use the group parameters to set variables local to the group you
are entering.  If you want to turn threading off in @samp{news.answers},
you could put @code{(gnus-show-threads nil)} in the group parameters of
that group.  @code{gnus-show-threads} will be made into a local variable
in the summary buffer you enter, and the form @code{nil} will be
@code{eval}ed there.

Note that this feature sets the variable locally to the summary buffer
if and only if @var{variable} has been bound as a variable.  Otherwise,
only evaluating the form will take place.  So, you may want to bind the
variable in advance using @code{defvar} or other if the result of the
form needs to be set to it.

But some variables are evaluated in the article buffer, or in the
message buffer (of a reply or followup or otherwise newly created
message).  As a workaround, it might help to add the variable in
question to @code{gnus-newsgroup-variables}.  @xref{Various Summary
Stuff}.  So if you want to set @code{message-from-style} via the group
parameters, then you may need the following statement elsewhere in your
@file{~/.gnus.el} file:

@lisp
(add-to-list 'gnus-newsgroup-variables 'message-from-style)
@end lisp

@vindex gnus-list-identifiers
A use for this feature is to remove a mailing list identifier tag in
the subject fields of articles.  E.g., if the news group

@example
nntp+news.gnus.org:gmane.text.docbook.apps
@end example

has the tag @samp{DOC-BOOK-APPS:} in the subject of all articles, this
tag can be removed from the article subjects in the summary buffer for
the group by putting @code{(gnus-list-identifiers "DOCBOOK-APPS:")}
into the group parameters for the group.

This can also be used as a group-specific hook function.  If you want to
hear a beep when you enter a group, you could put something like
@code{(dummy-variable (ding))} in the parameters of that group.  If
@code{dummy-variable} has been bound (see above), it will be set to the
(meaningless) result of the @code{(ding)} form.

Alternatively, since the VARIABLE becomes local to the group, this
pattern can be used to temporarily change a hook.  For example, if the
following is added to a group parameter

@lisp
(gnus-summary-prepared-hook
  (lambda nil (local-set-key "d" (local-key-binding "n"))))
@end lisp

when the group is entered, the 'd' key will not mark the article as
expired.

@end table

@vindex gnus-parameters
Group parameters can be set via the @code{gnus-parameters} variable too.
But some variables, such as @code{visible}, have no effect (For this
case see @code{gnus-permanently-visible-groups} as an alternative.).
For example:

@lisp
(setq gnus-parameters
      '(("mail\\..*"
         (gnus-show-threads nil)
         (gnus-use-scoring nil)
         (gnus-summary-line-format
          "%U%R%z%I%(%[%d:%ub%-23,23f%]%) %s\n")
         (gcc-self . t)
         (display . all))

        ("^nnimap:\\(foo.bar\\)$"
         (to-group . "\\1"))

        ("mail\\.me"
         (gnus-use-scoring t))

        ("list\\..*"
         (total-expire . t)
         (broken-reply-to . t))))
@end lisp

All clauses that matches the group name will be used, but the last
setting ``wins''.  So if you have two clauses that both match the
group name, and both set, say @code{display}, the last setting will
override the first.

Parameters that are strings will be subjected to regexp substitution,
as the @code{to-group} example shows.

@vindex gnus-parameters-case-fold-search
By default, whether comparing the group name and one of those regexps
specified in @code{gnus-parameters} is done in a case-sensitive manner
or a case-insensitive manner depends on the value of
@code{case-fold-search} at the time when the comparison is done.  The
value of @code{case-fold-search} is typically @code{t}; it means, for
example, the element @code{("INBOX\\.FOO" (total-expire . t))} might be
applied to both the @samp{INBOX.FOO} group and the @samp{INBOX.foo}
group.  If you want to make those regexps always case-sensitive, set the
value of the @code{gnus-parameters-case-fold-search} variable to
@code{nil}.  Otherwise, set it to @code{t} if you want to compare them
always in a case-insensitive manner.

You can define different sorting to different groups via
@code{gnus-parameters}.  Here is an example to sort an @acronym{NNTP}
group by reverse date to see the latest news at the top and an
@acronym{RSS} group by subject.  In this example, the first group is the
Debian daily news group @code{gmane.linux.debian.user.news} from
news.gmane.org.  The @acronym{RSS} group corresponds to the Debian
weekly news RSS feed
@url{http://packages.debian.org/unstable/newpkg_main.en.rdf},
@xref{RSS}.

@lisp
(setq
 gnus-parameters
 '(("nntp.*gmane\\.debian\\.user\\.news"
    (gnus-show-threads nil)
    (gnus-article-sort-functions '((not gnus-article-sort-by-date)))
    (gnus-use-adaptive-scoring nil)
    (gnus-use-scoring nil))
   ("nnrss.*debian"
    (gnus-show-threads nil)
    (gnus-article-sort-functions 'gnus-article-sort-by-subject)
    (gnus-use-adaptive-scoring nil)
    (gnus-use-scoring t)
    (gnus-score-find-score-files-function 'gnus-score-find-single)
    (gnus-summary-line-format "%U%R%z%d %I%(%[ %s %]%)\n"))))
@end lisp


@node Listing Groups
@section Listing Groups
@cindex group listing

These commands all list various slices of the groups available.

@table @kbd

@item l
@itemx A s
@kindex A s (Group)
@kindex l (Group)
@findex gnus-group-list-groups
List all groups that have unread articles
(@code{gnus-group-list-groups}).  If the numeric prefix is used, this
command will list only groups of level ARG and lower.  By default, it
only lists groups of level five (i.e.,
@code{gnus-group-default-list-level}) or lower (i.e., just subscribed
groups).

@item L
@itemx A u
@kindex A u (Group)
@kindex L (Group)
@findex gnus-group-list-all-groups
List all groups, whether they have unread articles or not
(@code{gnus-group-list-all-groups}).  If the numeric prefix is used,
this command will list only groups of level ARG and lower.  By default,
it lists groups of level seven or lower (i.e., just subscribed and
unsubscribed groups).

@item A l
@kindex A l (Group)
@findex gnus-group-list-level
List all unread groups on a specific level
(@code{gnus-group-list-level}).  If given a prefix, also list the groups
with no unread articles.

@item A k
@kindex A k (Group)
@findex gnus-group-list-killed
List all killed groups (@code{gnus-group-list-killed}).  If given a
prefix argument, really list all groups that are available, but aren't
currently (un)subscribed.  This could entail reading the active file
from the server.

@item A z
@kindex A z (Group)
@findex gnus-group-list-zombies
List all zombie groups (@code{gnus-group-list-zombies}).

@item A m
@kindex A m (Group)
@findex gnus-group-list-matching
List all unread, subscribed groups with names that match a regexp
(@code{gnus-group-list-matching}).

@item A M
@kindex A M (Group)
@findex gnus-group-list-all-matching
List groups that match a regexp (@code{gnus-group-list-all-matching}).

@item A A
@kindex A A (Group)
@findex gnus-group-list-active
List absolutely all groups in the active file(s) of the
server(s) you are connected to (@code{gnus-group-list-active}).  This
might very well take quite a while.  It might actually be a better idea
to do a @kbd{A M} to list all matching, and just give @samp{.} as the
thing to match on.  Also note that this command may list groups that
don't exist (yet)---these will be listed as if they were killed groups.
Take the output with some grains of salt.

@item A a
@kindex A a (Group)
@findex gnus-group-apropos
List all groups that have names that match a regexp
(@code{gnus-group-apropos}).

@item A d
@kindex A d (Group)
@findex gnus-group-description-apropos
List all groups that have names or descriptions that match a regexp
(@code{gnus-group-description-apropos}).

@item A c
@kindex A c (Group)
@findex gnus-group-list-cached
List all groups with cached articles (@code{gnus-group-list-cached}).

@item A ?
@kindex A ? (Group)
@findex gnus-group-list-dormant
List all groups with dormant articles (@code{gnus-group-list-dormant}).

@item A !
@kindex A ! (Group)
@findex gnus-group-list-ticked
List all groups with ticked articles (@code{gnus-group-list-ticked}).

@item A /
@kindex A / (Group)
@findex gnus-group-list-limit
Further limit groups within the current selection
(@code{gnus-group-list-limit}).  If you've first limited to groups
with dormant articles with @kbd{A ?}, you can then further limit with
@kbd{A / c}, which will then limit to groups with cached articles,
giving you the groups that have both dormant articles and cached
articles.

@item A f
@kindex A f (Group)
@findex gnus-group-list-flush
Flush groups from the current selection (@code{gnus-group-list-flush}).

@item A p
@kindex A p (Group)
@findex gnus-group-list-plus
List groups plus the current selection (@code{gnus-group-list-plus}).

@end table

@vindex gnus-permanently-visible-groups
@cindex visible group parameter
Groups that match the @code{gnus-permanently-visible-groups} regexp will
always be shown, whether they have unread articles or not.  You can also
add the @code{visible} element to the group parameters in question to
get the same effect.

@vindex gnus-list-groups-with-ticked-articles
Groups that have just ticked articles in it are normally listed in the
group buffer.  If @code{gnus-list-groups-with-ticked-articles} is
@code{nil}, these groups will be treated just like totally empty
groups.  It is @code{t} by default.


@node Sorting Groups
@section Sorting Groups
@cindex sorting groups

@kindex C-c C-s (Group)
@findex gnus-group-sort-groups
@vindex gnus-group-sort-function
The @kbd{C-c C-s} (@code{gnus-group-sort-groups}) command sorts the
group buffer according to the function(s) given by the
@code{gnus-group-sort-function} variable.  Available sorting functions
include:

@table @code

@item gnus-group-sort-by-alphabet
@findex gnus-group-sort-by-alphabet
Sort the group names alphabetically.  This is the default.

@item gnus-group-sort-by-real-name
@findex gnus-group-sort-by-real-name
Sort the group alphabetically on the real (unprefixed) group names.

@item gnus-group-sort-by-level
@findex gnus-group-sort-by-level
Sort by group level.

@item gnus-group-sort-by-score
@findex gnus-group-sort-by-score
Sort by group score.  @xref{Group Score}.

@item gnus-group-sort-by-rank
@findex gnus-group-sort-by-rank
Sort by group score and then the group level.  The level and the score
are, when taken together, the group's @dfn{rank}.  @xref{Group Score}.

@item gnus-group-sort-by-unread
@findex gnus-group-sort-by-unread
Sort by number of unread articles.

@item gnus-group-sort-by-method
@findex gnus-group-sort-by-method
Sort alphabetically on the select method.

@item gnus-group-sort-by-server
@findex gnus-group-sort-by-server
Sort alphabetically on the Gnus server name.


@end table

@code{gnus-group-sort-function} can also be a list of sorting
functions.  In that case, the most significant sort key function must be
the last one.


There are also a number of commands for sorting directly according to
some sorting criteria:

@table @kbd
@item G S a
@kindex G S a (Group)
@findex gnus-group-sort-groups-by-alphabet
Sort the group buffer alphabetically by group name
(@code{gnus-group-sort-groups-by-alphabet}).

@item G S u
@kindex G S u (Group)
@findex gnus-group-sort-groups-by-unread
Sort the group buffer by the number of unread articles
(@code{gnus-group-sort-groups-by-unread}).

@item G S l
@kindex G S l (Group)
@findex gnus-group-sort-groups-by-level
Sort the group buffer by group level
(@code{gnus-group-sort-groups-by-level}).

@item G S v
@kindex G S v (Group)
@findex gnus-group-sort-groups-by-score
Sort the group buffer by group score
(@code{gnus-group-sort-groups-by-score}).  @xref{Group Score}.

@item G S r
@kindex G S r (Group)
@findex gnus-group-sort-groups-by-rank
Sort the group buffer by group rank
(@code{gnus-group-sort-groups-by-rank}).  @xref{Group Score}.

@item G S m
@kindex G S m (Group)
@findex gnus-group-sort-groups-by-method
Sort the group buffer alphabetically by back end name@*
(@code{gnus-group-sort-groups-by-method}).

@item G S n
@kindex G S n (Group)
@findex gnus-group-sort-groups-by-real-name
Sort the group buffer alphabetically by real (unprefixed) group name
(@code{gnus-group-sort-groups-by-real-name}).

@end table

All the commands below obey the process/prefix convention
(@pxref{Process/Prefix}).

When given a symbolic prefix (@pxref{Symbolic Prefixes}), all these
commands will sort in reverse order.

You can also sort a subset of the groups:

@table @kbd
@item G P a
@kindex G P a (Group)
@findex gnus-group-sort-selected-groups-by-alphabet
Sort the groups alphabetically by group name
(@code{gnus-group-sort-selected-groups-by-alphabet}).

@item G P u
@kindex G P u (Group)
@findex gnus-group-sort-selected-groups-by-unread
Sort the groups by the number of unread articles
(@code{gnus-group-sort-selected-groups-by-unread}).

@item G P l
@kindex G P l (Group)
@findex gnus-group-sort-selected-groups-by-level
Sort the groups by group level
(@code{gnus-group-sort-selected-groups-by-level}).

@item G P v
@kindex G P v (Group)
@findex gnus-group-sort-selected-groups-by-score
Sort the groups by group score
(@code{gnus-group-sort-selected-groups-by-score}).  @xref{Group Score}.

@item G P r
@kindex G P r (Group)
@findex gnus-group-sort-selected-groups-by-rank
Sort the groups by group rank
(@code{gnus-group-sort-selected-groups-by-rank}).  @xref{Group Score}.

@item G P m
@kindex G P m (Group)
@findex gnus-group-sort-selected-groups-by-method
Sort the groups alphabetically by back end name@*
(@code{gnus-group-sort-selected-groups-by-method}).

@item G P n
@kindex G P n (Group)
@findex gnus-group-sort-selected-groups-by-real-name
Sort the groups alphabetically by real (unprefixed) group name
(@code{gnus-group-sort-selected-groups-by-real-name}).

@item G P s
@kindex G P s (Group)
@findex gnus-group-sort-selected-groups
Sort the groups according to @code{gnus-group-sort-function}.

@end table

And finally, note that you can use @kbd{C-k} and @kbd{C-y} to manually
move groups around.


@node Group Maintenance
@section Group Maintenance
@cindex bogus groups

@table @kbd
@item b
@kindex b (Group)
@findex gnus-group-check-bogus-groups
Find bogus groups and delete them
(@code{gnus-group-check-bogus-groups}).

@item F
@kindex F (Group)
@findex gnus-group-find-new-groups
Find new groups and process them (@code{gnus-group-find-new-groups}).
With 1 @kbd{C-u}, use the @code{ask-server} method to query the server
for new groups.  With 2 @kbd{C-u}'s, use most complete method possible
to query the server for new groups, and subscribe the new groups as
zombies.

@item C-c C-x
@kindex C-c C-x (Group)
@findex gnus-group-expire-articles
@cindex expiring mail
Run all expirable articles in the current group through the expiry
process (if any) (@code{gnus-group-expire-articles}).  That is, delete
all expirable articles in the group that have been around for a while.
(@pxref{Expiring Mail}).

@item C-c C-M-x
@kindex C-c C-M-x (Group)
@findex gnus-group-expire-all-groups
@cindex expiring mail
Run all expirable articles in all groups through the expiry process
(@code{gnus-group-expire-all-groups}).

@end table


@node Browse Foreign Server
@section Browse Foreign Server
@cindex foreign servers
@cindex browsing servers

@table @kbd
@item B
@kindex B (Group)
@findex gnus-group-browse-foreign-server
You will be queried for a select method and a server name.  Gnus will
then attempt to contact this server and let you browse the groups there
(@code{gnus-group-browse-foreign-server}).
@end table

@findex gnus-browse-mode
A new buffer with a list of available groups will appear.  This buffer
will use the @code{gnus-browse-mode}.  This buffer looks a bit (well,
a lot) like a normal group buffer.

Here's a list of keystrokes available in the browse mode:

@table @kbd
@item n
@kindex n (Browse)
@findex gnus-group-next-group
Go to the next group (@code{gnus-group-next-group}).

@item p
@kindex p (Browse)
@findex gnus-group-prev-group
Go to the previous group (@code{gnus-group-prev-group}).

@item SPACE
@kindex SPACE (Browse)
@findex gnus-browse-read-group
Enter the current group and display the first article
(@code{gnus-browse-read-group}).

@item RET
@kindex RET (Browse)
@findex gnus-browse-select-group
Enter the current group (@code{gnus-browse-select-group}).

@item u
@kindex u (Browse)
@findex gnus-browse-unsubscribe-current-group
@vindex gnus-browse-subscribe-newsgroup-method
Unsubscribe to the current group, or, as will be the case here,
subscribe to it (@code{gnus-browse-unsubscribe-current-group}).  You
can affect the way the new group is entered into the Group buffer
using the variable @code{gnus-browse-subscribe-newsgroup-method}.  See
@pxref{Subscription Methods} for available options.

@item l
@itemx q
@kindex q (Browse)
@kindex l (Browse)
@findex gnus-browse-exit
Exit browse mode (@code{gnus-browse-exit}).

@item d
@kindex d (Browse)
@findex gnus-browse-describe-group
Describe the current group (@code{gnus-browse-describe-group}).

@item ?
@kindex ? (Browse)
@findex gnus-browse-describe-briefly
Describe browse mode briefly (well, there's not much to describe, is
there) (@code{gnus-browse-describe-briefly}).

@item DEL
@kindex DEL (Browse)
@findex gnus-browse-delete-group
This function will delete the current group
(@code{gnus-browse-delete-group}).  If given a prefix, this function
will actually delete all the articles in the group, and forcibly
remove the group itself from the face of the Earth.  Use a prefix only
if you are absolutely sure of what you are doing.
@end table


@node Exiting Gnus
@section Exiting Gnus
@cindex exiting Gnus

Yes, Gnus is ex(c)iting.

@table @kbd
@item z
@kindex z (Group)
@findex gnus-group-suspend
Suspend Gnus (@code{gnus-group-suspend}).  This doesn't really exit Gnus,
but it kills all buffers except the Group buffer.  I'm not sure why this
is a gain, but then who am I to judge?

@item q
@kindex q (Group)
@findex gnus-group-exit
@c @icon{gnus-group-exit}
Quit Gnus (@code{gnus-group-exit}).

@item Q
@kindex Q (Group)
@findex gnus-group-quit
Quit Gnus without saving the @file{.newsrc} files (@code{gnus-group-quit}).
The dribble file will be saved, though (@pxref{Auto Save}).
@end table

@vindex gnus-exit-gnus-hook
@vindex gnus-suspend-gnus-hook
@vindex gnus-after-exiting-gnus-hook
@code{gnus-suspend-gnus-hook} is called when you suspend Gnus and
@code{gnus-exit-gnus-hook} is called when you quit Gnus, while
@code{gnus-after-exiting-gnus-hook} is called as the final item when
exiting Gnus.

Note:

@quotation
Miss Lisa Cannifax, while sitting in English class, felt her feet go
numbly heavy and herself fall into a hazy trance as the boy sitting
behind her drew repeated lines with his pencil across the back of her
plastic chair.
@end quotation


@node Group Topics
@section Group Topics
@cindex topics

If you read lots and lots of groups, it might be convenient to group
them hierarchically according to topics.  You put your Emacs groups over
here, your sex groups over there, and the rest (what, two groups or so?)
you put in some misc section that you never bother with anyway.  You can
even group the Emacs sex groups as a sub-topic to either the Emacs
groups or the sex groups---or both!  Go wild!

@iftex
@iflatex
\gnusfigure{Group Topics}{400}{
\put(75,50){\epsfig{figure=ps/group-topic,height=9cm}}
}
@end iflatex
@end iftex

Here's an example:

@example
Gnus
  Emacs -- I wuw it!
     3: comp.emacs
     2: alt.religion.emacs
    Naughty Emacs
     452: alt.sex.emacs
       0: comp.talk.emacs.recovery
  Misc
     8: comp.binaries.fractals
    13: comp.sources.unix
@end example

@findex gnus-topic-mode
@kindex t (Group)
To get this @emph{fab} functionality you simply turn on (ooh!) the
@code{gnus-topic} minor mode---type @kbd{t} in the group buffer.  (This
is a toggling command.)

Go ahead, just try it.  I'll still be here when you get back.  La de
dum@dots{} Nice tune, that@dots{} la la la@dots{} What, you're back?
Yes, and now press @kbd{l}.  There.  All your groups are now listed
under @samp{misc}.  Doesn't that make you feel all warm and fuzzy?
Hot and bothered?

If you want this permanently enabled, you should add that minor mode to
the hook for the group mode.  Put the following line in your
@file{~/.gnus.el} file:

@lisp
(add-hook 'gnus-group-mode-hook 'gnus-topic-mode)
@end lisp

@menu
* Topic Commands::              Interactive E-Z commands.
* Topic Variables::             How to customize the topics the Lisp Way.
* Topic Sorting::               Sorting each topic individually.
* Topic Topology::              A map of the world.
* Topic Parameters::            Parameters that apply to all groups in a topic.
@end menu


@node Topic Commands
@subsection Topic Commands
@cindex topic commands

When the topic minor mode is turned on, a new @kbd{T} submap will be
available.  In addition, a few of the standard keys change their
definitions slightly.

In general, the following kinds of operations are possible on topics.
First of all, you want to create topics.  Secondly, you want to put
groups in topics and to move them around until you have an order you
like.  The third kind of operation is to show/hide parts of the whole
shebang.  You might want to hide a topic including its subtopics and
groups, to get a better overview of the other groups.

Here is a list of the basic keys that you might need to set up topics
the way you like.

@table @kbd

@item T n
@kindex T n (Topic)
@findex gnus-topic-create-topic
Prompt for a new topic name and create it
(@code{gnus-topic-create-topic}).

@item T TAB
@itemx TAB
@kindex T TAB (Topic)
@kindex TAB (Topic)
@findex gnus-topic-indent
``Indent'' the current topic so that it becomes a sub-topic of the
previous topic (@code{gnus-topic-indent}).  If given a prefix,
``un-indent'' the topic instead.

@item M-TAB
@kindex M-TAB (Topic)
@findex gnus-topic-unindent
``Un-indent'' the current topic so that it becomes a sub-topic of the
parent of its current parent (@code{gnus-topic-unindent}).

@end table

The following two keys can be used to move groups and topics around.
They work like the well-known cut and paste.  @kbd{C-k} is like cut and
@kbd{C-y} is like paste.  Of course, this being Emacs, we use the terms
kill and yank rather than cut and paste.

@table @kbd

@item C-k
@kindex C-k (Topic)
@findex gnus-topic-kill-group
Kill a group or topic (@code{gnus-topic-kill-group}).  All groups in the
topic will be removed along with the topic.

@item C-y
@kindex C-y (Topic)
@findex gnus-topic-yank-group
Yank the previously killed group or topic
(@code{gnus-topic-yank-group}).  Note that all topics will be yanked
before all groups.

So, to move a topic to the beginning of the list of topics, just hit
@kbd{C-k} on it.  This is like the ``cut'' part of cut and paste.  Then,
move the cursor to the beginning of the buffer (just below the ``Gnus''
topic) and hit @kbd{C-y}.  This is like the ``paste'' part of cut and
paste.  Like I said---E-Z.

You can use @kbd{C-k} and @kbd{C-y} on groups as well as on topics.  So
you can move topics around as well as groups.

@end table

After setting up the topics the way you like them, you might wish to
hide a topic, or to show it again.  That's why we have the following
key.

@table @kbd

@item RET
@kindex RET (Topic)
@findex gnus-topic-select-group
@itemx SPACE
Either select a group or fold a topic (@code{gnus-topic-select-group}).
When you perform this command on a group, you'll enter the group, as
usual.  When done on a topic line, the topic will be folded (if it was
visible) or unfolded (if it was folded already).  So it's basically a
toggling command on topics.  In addition, if you give a numerical
prefix, group on that level (and lower) will be displayed.

@end table

Now for a list of other commands, in no particular order.

@table @kbd

@item T m
@kindex T m (Topic)
@findex gnus-topic-move-group
Move the current group to some other topic
(@code{gnus-topic-move-group}).  This command uses the process/prefix
convention (@pxref{Process/Prefix}).

@item T j
@kindex T j (Topic)
@findex gnus-topic-jump-to-topic
Go to a topic (@code{gnus-topic-jump-to-topic}).

@item T c
@kindex T c (Topic)
@findex gnus-topic-copy-group
Copy the current group to some other topic
(@code{gnus-topic-copy-group}).  This command uses the process/prefix
convention (@pxref{Process/Prefix}).

@item T h
@kindex T h (Topic)
@findex gnus-topic-hide-topic
Hide the current topic (@code{gnus-topic-hide-topic}).  If given
a prefix, hide the topic permanently.

@item T s
@kindex T s (Topic)
@findex gnus-topic-show-topic
Show the current topic (@code{gnus-topic-show-topic}).  If given
a prefix, show the topic permanently.

@item T D
@kindex T D (Topic)
@findex gnus-topic-remove-group
Remove a group from the current topic (@code{gnus-topic-remove-group}).
This command is mainly useful if you have the same group in several
topics and wish to remove it from one of the topics.  You may also
remove a group from all topics, but in that case, Gnus will add it to
the root topic the next time you start Gnus.  In fact, all new groups
(which, naturally, don't belong to any topic) will show up in the root
topic.

This command uses the process/prefix convention
(@pxref{Process/Prefix}).

@item T M
@kindex T M (Topic)
@findex gnus-topic-move-matching
Move all groups that match some regular expression to a topic
(@code{gnus-topic-move-matching}).

@item T C
@kindex T C (Topic)
@findex gnus-topic-copy-matching
Copy all groups that match some regular expression to a topic
(@code{gnus-topic-copy-matching}).

@item T H
@kindex T H (Topic)
@findex gnus-topic-toggle-display-empty-topics
Toggle hiding empty topics
(@code{gnus-topic-toggle-display-empty-topics}).

@item T #
@kindex T # (Topic)
@findex gnus-topic-mark-topic
Mark all groups in the current topic with the process mark
(@code{gnus-topic-mark-topic}).  This command works recursively on
sub-topics unless given a prefix.

@item T M-#
@kindex T M-# (Topic)
@findex gnus-topic-unmark-topic
Remove the process mark from all groups in the current topic
(@code{gnus-topic-unmark-topic}).  This command works recursively on
sub-topics unless given a prefix.

@item C-c C-x
@kindex C-c C-x (Topic)
@findex gnus-topic-expire-articles
@cindex expiring mail
Run all expirable articles in the current group or topic through the
expiry process (if any)
(@code{gnus-topic-expire-articles}).  (@pxref{Expiring Mail}).

@item T r
@kindex T r (Topic)
@findex gnus-topic-rename
Rename a topic (@code{gnus-topic-rename}).

@item T DEL
@kindex T DEL (Topic)
@findex gnus-topic-delete
Delete an empty topic (@code{gnus-topic-delete}).

@item A T
@kindex A T (Topic)
@findex gnus-topic-list-active
List all groups that Gnus knows about in a topics-ified way
(@code{gnus-topic-list-active}).

@item T M-n
@kindex T M-n (Topic)
@findex gnus-topic-goto-next-topic
Go to the next topic (@code{gnus-topic-goto-next-topic}).

@item T M-p
@kindex T M-p (Topic)
@findex gnus-topic-goto-previous-topic
Go to the previous topic (@code{gnus-topic-goto-previous-topic}).

@item G p
@kindex G p (Topic)
@findex gnus-topic-edit-parameters
@cindex group parameters
@cindex topic parameters
@cindex parameters
Edit the topic parameters (@code{gnus-topic-edit-parameters}).
@xref{Topic Parameters}.

@end table


@node Topic Variables
@subsection Topic Variables
@cindex topic variables

The previous section told you how to tell Gnus which topics to display.
This section explains how to tell Gnus what to display about each topic.

@vindex gnus-topic-line-format
The topic lines themselves are created according to the
@code{gnus-topic-line-format} variable (@pxref{Formatting Variables}).
Valid elements are:

@table @samp
@item i
Indentation.
@item n
Topic name.
@item v
Visibility.
@item l
Level.
@item g
Number of groups in the topic.
@item a
Number of unread articles in the topic.
@item A
Number of unread articles in the topic and all its subtopics.
@end table

@vindex gnus-topic-indent-level
Each sub-topic (and the groups in the sub-topics) will be indented with
@code{gnus-topic-indent-level} times the topic level number of spaces.
The default is 2.

@vindex gnus-topic-mode-hook
@code{gnus-topic-mode-hook} is called in topic minor mode buffers.

@vindex gnus-topic-display-empty-topics
The @code{gnus-topic-display-empty-topics} says whether to display even
topics that have no unread articles in them.  The default is @code{t}.


@node Topic Sorting
@subsection Topic Sorting
@cindex topic sorting

You can sort the groups in each topic individually with the following
commands:


@table @kbd
@item T S a
@kindex T S a (Topic)
@findex gnus-topic-sort-groups-by-alphabet
Sort the current topic alphabetically by group name
(@code{gnus-topic-sort-groups-by-alphabet}).

@item T S u
@kindex T S u (Topic)
@findex gnus-topic-sort-groups-by-unread
Sort the current topic by the number of unread articles
(@code{gnus-topic-sort-groups-by-unread}).

@item T S l
@kindex T S l (Topic)
@findex gnus-topic-sort-groups-by-level
Sort the current topic by group level
(@code{gnus-topic-sort-groups-by-level}).

@item T S v
@kindex T S v (Topic)
@findex gnus-topic-sort-groups-by-score
Sort the current topic by group score
(@code{gnus-topic-sort-groups-by-score}).  @xref{Group Score}.

@item T S r
@kindex T S r (Topic)
@findex gnus-topic-sort-groups-by-rank
Sort the current topic by group rank
(@code{gnus-topic-sort-groups-by-rank}).  @xref{Group Score}.

@item T S m
@kindex T S m (Topic)
@findex gnus-topic-sort-groups-by-method
Sort the current topic alphabetically by back end name
(@code{gnus-topic-sort-groups-by-method}).

@item T S e
@kindex T S e (Topic)
@findex gnus-topic-sort-groups-by-server
Sort the current topic alphabetically by server name
(@code{gnus-topic-sort-groups-by-server}).

@item T S s
@kindex T S s (Topic)
@findex gnus-topic-sort-groups
Sort the current topic according to the function(s) given by the
@code{gnus-group-sort-function} variable
(@code{gnus-topic-sort-groups}).

@end table

When given a prefix argument, all these commands will sort in reverse
order.  @xref{Sorting Groups}, for more information about group
sorting.


@node Topic Topology
@subsection Topic Topology
@cindex topic topology
@cindex topology

So, let's have a look at an example group buffer:

@example
@group
Gnus
  Emacs -- I wuw it!
     3: comp.emacs
     2: alt.religion.emacs
    Naughty Emacs
     452: alt.sex.emacs
       0: comp.talk.emacs.recovery
  Misc
     8: comp.binaries.fractals
    13: comp.sources.unix
@end group
@end example

So, here we have one top-level topic (@samp{Gnus}), two topics under
that, and one sub-topic under one of the sub-topics.  (There is always
just one (1) top-level topic).  This topology can be expressed as
follows:

@lisp
(("Gnus" visible)
 (("Emacs -- I wuw it!" visible)
  (("Naughty Emacs" visible)))
 (("Misc" visible)))
@end lisp

@vindex gnus-topic-topology
This is in fact how the variable @code{gnus-topic-topology} would look
for the display above.  That variable is saved in the @file{.newsrc.eld}
file, and shouldn't be messed with manually---unless you really want
to.  Since this variable is read from the @file{.newsrc.eld} file,
setting it in any other startup files will have no effect.

This topology shows what topics are sub-topics of what topics (right),
and which topics are visible.  Two settings are currently
allowed---@code{visible} and @code{invisible}.


@node Topic Parameters
@subsection Topic Parameters
@cindex topic parameters

All groups in a topic will inherit group parameters from the parent
(and ancestor) topic parameters.  All valid group parameters are valid
topic parameters (@pxref{Group Parameters}).  When the agent is
enabled, all agent parameters (See Agent Parameters in @ref{Category
Syntax}) are also valid topic parameters.

In addition, the following parameters are only valid as topic
parameters:

@table @code
@item subscribe
When subscribing new groups by topic (@pxref{Subscription Methods}), the
@code{subscribe} topic parameter says what groups go in what topic.  Its
value should be a regexp to match the groups that should go in that
topic.

@item subscribe-level
When subscribing new groups by topic (see the @code{subscribe} parameter),
the group will be subscribed with the level specified in the
@code{subscribe-level} instead of @code{gnus-level-default-subscribed}.

@end table

Group parameters (of course) override topic parameters, and topic
parameters in sub-topics override topic parameters in super-topics.  You
know.  Normal inheritance rules.  (@dfn{Rules} is here a noun, not a
verb, although you may feel free to disagree with me here.)

@example
@group
Gnus
  Emacs
     3: comp.emacs
     2: alt.religion.emacs
   452: alt.sex.emacs
    Relief
     452: alt.sex.emacs
       0: comp.talk.emacs.recovery
  Misc
     8: comp.binaries.fractals
    13: comp.sources.unix
   452: alt.sex.emacs
@end group
@end example

The @samp{Emacs} topic has the topic parameter @code{(score-file
. "emacs.SCORE")}; the @samp{Relief} topic has the topic parameter
@code{(score-file . "relief.SCORE")}; and the @samp{Misc} topic has the
topic parameter @code{(score-file . "emacs.SCORE")}.  In addition,
@* @samp{alt.religion.emacs} has the group parameter @code{(score-file
. "religion.SCORE")}.

Now, when you enter @samp{alt.sex.emacs} in the @samp{Relief} topic, you
will get the @file{relief.SCORE} home score file.  If you enter the same
group in the @samp{Emacs} topic, you'll get the @file{emacs.SCORE} home
score file.  If you enter the group @samp{alt.religion.emacs}, you'll
get the @file{religion.SCORE} home score file.

This seems rather simple and self-evident, doesn't it?  Well, yes.  But
there are some problems, especially with the @code{total-expiry}
parameter.  Say you have a mail group in two topics; one with
@code{total-expiry} and one without.  What happens when you do @kbd{M-x
gnus-expire-all-expirable-groups}?  Gnus has no way of telling which one
of these topics you mean to expire articles from, so anything may
happen.  In fact, I hereby declare that it is @dfn{undefined} what
happens.  You just have to be careful if you do stuff like that.


@node Non-ASCII Group Names
@section Accessing groups of non-English names
@cindex non-ascii group names

There are some news servers that provide groups of which the names are
expressed with their native languages in the world.  For instance, in a
certain news server there are some newsgroups of which the names are
spelled in Chinese, where people are talking in Chinese.  You can, of
course, subscribe to such news groups using Gnus.  Currently Gnus
supports non-@acronym{ASCII} group names not only with the @code{nntp}
back end but also with the @code{nnml} back end and the @code{nnrss}
back end.

Every such group name is encoded by a certain charset in the server
side (in an @acronym{NNTP} server its administrator determines the
charset, but for groups in the other back ends it is determined by you).
Gnus has to display the decoded ones for you in the group buffer and the
article buffer, and needs to use the encoded ones when communicating
with servers.  However, Gnus doesn't know what charset is used for each
non-@acronym{ASCII} group name.  The following two variables are just
the ones for telling Gnus what charset should be used for each group:

@table @code
@item gnus-group-name-charset-method-alist
@vindex gnus-group-name-charset-method-alist
An alist of select methods and charsets.  The default value is
@code{nil}.  The names of groups in the server specified by that select
method are all supposed to use the corresponding charset.  For example:

@lisp
(setq gnus-group-name-charset-method-alist
      '(((nntp "news.com.cn") . cn-gb-2312)))
@end lisp

Charsets specified for groups with this variable are preferred to the
ones specified for the same groups with the
@code{gnus-group-name-charset-group-alist} variable (see below).

A select method can be very long, like:

@lisp
(nntp "gmane"
      (nntp-address "news.gmane.org")
      (nntp-end-of-line "\n")
      (nntp-open-connection-function
       nntp-open-via-rlogin-and-telnet)
      (nntp-via-rlogin-command "ssh")
      (nntp-via-rlogin-command-switches
       ("-C" "-t" "-e" "none"))
      (nntp-via-address @dots{}))
@end lisp

In that case, you can truncate it into @code{(nntp "gmane")} in this
variable.  That is, it is enough to contain only the back end name and
the server name.

@item gnus-group-name-charset-group-alist
@cindex UTF-8 group names
@vindex gnus-group-name-charset-group-alist
An alist of regexp of group name and the charset for group names.
@code{((".*" . utf-8))} is the default value if UTF-8 is supported,
otherwise the default is @code{nil}.  For example:

@lisp
(setq gnus-group-name-charset-group-alist
      '(("\\.com\\.cn:" . cn-gb-2312)
        (".*" . utf-8)))
@end lisp

Note that this variable is ignored if the match is made with
@code{gnus-group-name-charset-method-alist}.
@end table

Those two variables are used also to determine the charset for encoding
and decoding non-@acronym{ASCII} group names that are in the back ends
other than @code{nntp}.  It means that it is you who determine it.  If
you do nothing, the charset used for group names in those back ends will
all be @code{utf-8} because of the last element of
@code{gnus-group-name-charset-group-alist}.

There is one more important variable for non-@acronym{ASCII} group
names:

@table @code
@item nnmail-pathname-coding-system
@vindex nnmail-pathname-coding-system
The value of this variable should be a coding system or @code{nil}.  The
default is @code{nil} in Emacs, or is the aliasee of the coding system
named @code{file-name} (a certain coding system of which an alias is
@code{file-name}) in XEmacs.

The @code{nnml} back end, the @code{nnrss} back end, the agent, and
the cache use non-@acronym{ASCII} group names in those files and
directories.  This variable overrides the value of
@code{file-name-coding-system} which specifies the coding system used
when encoding and decoding those file names and directory names.

In XEmacs (with the @code{mule} feature), @code{file-name-coding-system}
is the only means to specify the coding system used to encode and decode
file names.  On the other hand, Emacs uses the value of
@code{default-file-name-coding-system} if @code{file-name-coding-system}
is @code{nil} or it is bound to the value of
@code{nnmail-pathname-coding-system} which is @code{nil}.

Normally the value of @code{default-file-name-coding-system} in Emacs or
@code{nnmail-pathname-coding-system} in XEmacs is initialized according
to the locale, so you will need to do nothing if the value is suitable
to encode and decode non-@acronym{ASCII} group names.

The value of this variable (or @code{default-file-name-coding-system})
does not necessarily need to be the same value that is determined by
@code{gnus-group-name-charset-method-alist} and
@code{gnus-group-name-charset-group-alist}.

If @code{default-file-name-coding-system} or this variable is
initialized by default to @code{iso-latin-1} for example, although you
want to subscribe to the groups spelled in Chinese, that is the most
typical case where you have to customize
@code{nnmail-pathname-coding-system}.  The @code{utf-8} coding system is
a good candidate for it.  Otherwise, you may change the locale in your
system so that @code{default-file-name-coding-system} or this variable
may be initialized to an appropriate value.
@end table

Note that when you copy or move articles from a non-@acronym{ASCII}
group to another group, the charset used to encode and decode group
names should be the same in both groups.  Otherwise the Newsgroups
header will be displayed incorrectly in the article buffer.


@node Misc Group Stuff
@section Misc Group Stuff

@menu
* Scanning New Messages::       Asking Gnus to see whether new messages have arrived.
* Group Information::           Information and help on groups and Gnus.
* Group Timestamp::             Making Gnus keep track of when you last read a group.
* File Commands::               Reading and writing the Gnus files.
* Sieve Commands::              Managing Sieve scripts.
@end menu

@table @kbd

@item v
@kindex v (Group)
@cindex keys, reserved for users (Group)
The key @kbd{v} is reserved for users.  You can bind it to some
command or better use it as a prefix key.  For example:

@lisp
(define-key gnus-group-mode-map (kbd "v j d")
  (lambda ()
    (interactive)
    (gnus-group-jump-to-group "nndraft:drafts")))
@end lisp

On keys reserved for users in Emacs and on keybindings in general
@xref{Keymaps, Keymaps, , emacs, The Emacs Editor}.

@item ^
@kindex ^ (Group)
@findex gnus-group-enter-server-mode
Enter the server buffer (@code{gnus-group-enter-server-mode}).
@xref{Server Buffer}.

@item a
@kindex a (Group)
@findex gnus-group-post-news
Start composing a message (a news by default)
(@code{gnus-group-post-news}).  If given a prefix, post to the group
under the point.  If the prefix is 1, prompt for a group to post to.
Contrary to what the name of this function suggests, the prepared
article might be a mail instead of a news, if a mail group is specified
with the prefix argument.  @xref{Composing Messages}.

@item m
@kindex m (Group)
@findex gnus-group-mail
Mail a message somewhere (@code{gnus-group-mail}).  If given a prefix,
use the posting style of the group under the point.  If the prefix is 1,
prompt for a group name to find the posting style.
@xref{Composing Messages}.

@item i
@kindex i (Group)
@findex gnus-group-news
Start composing a news (@code{gnus-group-news}).  If given a prefix,
post to the group under the point.  If the prefix is 1, prompt
for group to post to.  @xref{Composing Messages}.

This function actually prepares a news even when using mail groups.
This is useful for ``posting'' messages to mail groups without actually
sending them over the network: they're just saved directly to the group
in question.  The corresponding back end must have a request-post method
for this to work though.

@item G z
@kindex G z (Group)
@findex gnus-group-compact-group

Compact the group under point (@code{gnus-group-compact-group}).
Currently implemented only in nnml (@pxref{Mail Spool}).  This removes
gaps between article numbers, hence getting a correct total article
count.

@end table

Variables for the group buffer:

@table @code

@item gnus-group-mode-hook
@vindex gnus-group-mode-hook
is called after the group buffer has been
created.

@item gnus-group-prepare-hook
@vindex gnus-group-prepare-hook
is called after the group buffer is
generated.  It may be used to modify the buffer in some strange,
unnatural way.

@item gnus-group-prepared-hook
@vindex gnus-group-prepare-hook
is called as the very last thing after the group buffer has been
generated.  It may be used to move point around, for instance.

@item gnus-permanently-visible-groups
@vindex gnus-permanently-visible-groups
Groups matching this regexp will always be listed in the group buffer,
whether they are empty or not.

@end table

@node Scanning New Messages
@subsection Scanning New Messages
@cindex new messages
@cindex scanning new news

@table @kbd

@item g
@kindex g (Group)
@findex gnus-group-get-new-news
@c @icon{gnus-group-get-new-news}
Check the server(s) for new articles.  If the numerical prefix is used,
this command will check only groups of level @var{arg} and lower
(@code{gnus-group-get-new-news}).  If given a non-numerical prefix, this
command will force a total re-reading of the active file(s) from the
back end(s).

@item M-g
@kindex M-g (Group)
@findex gnus-group-get-new-news-this-group
@vindex gnus-goto-next-group-when-activating
@c @icon{gnus-group-get-new-news-this-group}
Check whether new articles have arrived in the current group
(@code{gnus-group-get-new-news-this-group}).
@code{gnus-goto-next-group-when-activating} says whether this command is
to move point to the next group or not.  It is @code{t} by default.

@findex gnus-activate-all-groups
@cindex activating groups
@item C-c M-g
@kindex C-c M-g (Group)
Activate absolutely all groups (@code{gnus-activate-all-groups}).

@item R
@kindex R (Group)
@cindex restarting
@findex gnus-group-restart
Restart Gnus (@code{gnus-group-restart}).  This saves the @file{.newsrc}
file(s), closes the connection to all servers, clears up all run-time
Gnus variables, and then starts Gnus all over again.

@end table

@vindex gnus-get-new-news-hook
@code{gnus-get-new-news-hook} is run just before checking for new news.

@vindex gnus-after-getting-new-news-hook
@code{gnus-after-getting-new-news-hook} is run after checking for new
news.


@node Group Information
@subsection Group Information
@cindex group information
@cindex information on groups

@table @kbd


@item H d
@itemx C-c C-d
@c @icon{gnus-group-describe-group}
@kindex H d (Group)
@kindex C-c C-d (Group)
@cindex describing groups
@cindex group description
@findex gnus-group-describe-group
Describe the current group (@code{gnus-group-describe-group}).  If given
a prefix, force Gnus to re-read the description from the server.

@item M-d
@kindex M-d (Group)
@findex gnus-group-describe-all-groups
Describe all groups (@code{gnus-group-describe-all-groups}).  If given a
prefix, force Gnus to re-read the description file from the server.

@item H v
@itemx V
@kindex V (Group)
@kindex H v (Group)
@cindex version
@findex gnus-version
Display current Gnus version numbers (@code{gnus-version}).

@item ?
@kindex ? (Group)
@findex gnus-group-describe-briefly
Give a very short help message (@code{gnus-group-describe-briefly}).

@item C-c C-i
@kindex C-c C-i (Group)
@cindex info
@cindex manual
@findex gnus-info-find-node
Go to the Gnus info node (@code{gnus-info-find-node}).
@end table


@node Group Timestamp
@subsection Group Timestamp
@cindex timestamps
@cindex group timestamps

It can be convenient to let Gnus keep track of when you last read a
group.  To set the ball rolling, you should add
@code{gnus-group-set-timestamp} to @code{gnus-select-group-hook}:

@lisp
(add-hook 'gnus-select-group-hook 'gnus-group-set-timestamp)
@end lisp

After doing this, each time you enter a group, it'll be recorded.

This information can be displayed in various ways---the easiest is to
use the @samp{%d} spec in the group line format:

@lisp
(setq gnus-group-line-format
      "%M\%S\%p\%P\%5y: %(%-40,40g%) %d\n")
@end lisp

This will result in lines looking like:

@example
*        0: mail.ding                                19961002T012943
         0: custom                                   19961002T012713
@end example

As you can see, the date is displayed in compact ISO 8601 format.  This
may be a bit too much, so to just display the date, you could say
something like:

@lisp
(setq gnus-group-line-format
      "%M\%S\%p\%P\%5y: %(%-40,40g%) %6,6~(cut 2)d\n")
@end lisp

If you would like greater control of the time format, you can use a
user-defined format spec.  Something like the following should do the
trick:

@lisp
(setq gnus-group-line-format
      "%M\%S\%p\%P\%5y: %(%-40,40g%) %ud\n")
(defun gnus-user-format-function-d (headers)
  (let ((time (gnus-group-timestamp gnus-tmp-group)))
    (if time
        (format-time-string "%b %d  %H:%M" time)
      "")))
@end lisp

To see what variables are dynamically bound (like
@code{gnus-tmp-group}), you have to look at the source code.  The
variable names aren't guaranteed to be stable over Gnus versions,
either.


@node File Commands
@subsection File Commands
@cindex file commands

@table @kbd

@item r
@kindex r (Group)
@findex gnus-group-read-init-file
@vindex gnus-init-file
@cindex reading init file
Re-read the init file (@code{gnus-init-file}, which defaults to
@file{~/.gnus.el}) (@code{gnus-group-read-init-file}).

@item s
@kindex s (Group)
@findex gnus-group-save-newsrc
@cindex saving .newsrc
Save the @file{.newsrc.eld} file (and @file{.newsrc} if wanted)
(@code{gnus-group-save-newsrc}).  If given a prefix, force saving the
file(s) whether Gnus thinks it is necessary or not.

@c @item Z
@c @kindex Z (Group)
@c @findex gnus-group-clear-dribble
@c Clear the dribble buffer (@code{gnus-group-clear-dribble}).

@end table


@node Sieve Commands
@subsection Sieve Commands
@cindex group sieve commands

Sieve is a server-side mail filtering language.  In Gnus you can use
the @code{sieve} group parameter (@pxref{Group Parameters}) to specify
sieve rules that should apply to each group.  Gnus provides two
commands to translate all these group parameters into a proper Sieve
script that can be transferred to the server somehow.

@vindex gnus-sieve-file
@vindex gnus-sieve-region-start
@vindex gnus-sieve-region-end
The generated Sieve script is placed in @code{gnus-sieve-file} (by
default @file{~/.sieve}).  The Sieve code that Gnus generate is placed
between two delimiters, @code{gnus-sieve-region-start} and
@code{gnus-sieve-region-end}, so you may write additional Sieve code
outside these delimiters that will not be removed the next time you
regenerate the Sieve script.

@vindex gnus-sieve-crosspost
The variable @code{gnus-sieve-crosspost} controls how the Sieve script
is generated.  If it is non-@code{nil} (the default) articles is
placed in all groups that have matching rules, otherwise the article
is only placed in the group with the first matching rule.  For
example, the group parameter @samp{(sieve address "sender"
"owner-ding@@hpc.uh.edu")} will generate the following piece of Sieve
code if @code{gnus-sieve-crosspost} is @code{nil}.  (When
@code{gnus-sieve-crosspost} is non-@code{nil}, it looks the same
except that the line containing the call to @code{stop} is removed.)

@example
if address "sender" "owner-ding@@hpc.uh.edu" @{
        fileinto "INBOX.ding";
        stop;
@}
@end example

@xref{Top, Emacs Sieve, Top, sieve, Emacs Sieve}.

@table @kbd

@item D g
@kindex D g (Group)
@findex gnus-sieve-generate
@vindex gnus-sieve-file
@cindex generating sieve script
Regenerate a Sieve script from the @code{sieve} group parameters and
put you into the @code{gnus-sieve-file} without saving it.

@item D u
@kindex D u (Group)
@findex gnus-sieve-update
@vindex gnus-sieve-file
@cindex updating sieve script
Regenerates the Gnus managed part of @code{gnus-sieve-file} using the
@code{sieve} group parameters, save the file and upload it to the
server using the @code{sieveshell} program.

@end table


@node Summary Buffer
@chapter Summary Buffer
@cindex summary buffer

A line for each article is displayed in the summary buffer.  You can
move around, read articles, post articles and reply to articles.

The most common way to a summary buffer is to select a group from the
group buffer (@pxref{Selecting a Group}).

You can have as many summary buffers open as you wish.

You can customize the Summary Mode tool bar, see @kbd{M-x
customize-apropos RET gnus-summary-tool-bar}.  This feature is only
available in Emacs.

@kindex v (Summary)
@cindex keys, reserved for users (Summary)
The key @kbd{v} is reserved for users.  You can bind it to some
command or better use it as a prefix key.  For example:
@lisp
(define-key gnus-summary-mode-map (kbd "v -") "LrS") ;; lower subthread
@end lisp

@menu
* Summary Buffer Format::       Deciding how the summary buffer is to look.
* Summary Maneuvering::         Moving around the summary buffer.
* Choosing Articles::           Reading articles.
* Paging the Article::          Scrolling the current article.
* Reply Followup and Post::     Posting articles.
* Delayed Articles::            Send articles at a later time.
* Marking Articles::            Marking articles as read, expirable, etc.
* Limiting::                    You can limit the summary buffer.
* Threading::                   How threads are made.
* Sorting the Summary Buffer::  How articles and threads are sorted.
* Asynchronous Fetching::       Gnus might be able to pre-fetch articles.
* Article Caching::             You may store articles in a cache.
* Persistent Articles::         Making articles expiry-resistant.
* Sticky Articles::             Article buffers that are not reused.
* Article Backlog::             Having already read articles hang around.
* Saving Articles::             Ways of customizing article saving.
* Decoding Articles::           Gnus can treat series of (uu)encoded articles.
* Article Treatment::           The article buffer can be mangled at will.
* MIME Commands::               Doing MIMEy things with the articles.
* Charsets::                    Character set issues.
* Article Commands::            Doing various things with the article buffer.
* Summary Sorting::             Sorting the summary buffer in various ways.
* Finding the Parent::          No child support? Get the parent.
* Alternative Approaches::      Reading using non-default summaries.
* Tree Display::                A more visual display of threads.
* Mail Group Commands::         Some commands can only be used in mail groups.
* Various Summary Stuff::       What didn't fit anywhere else.
* Exiting the Summary Buffer::  Returning to the Group buffer,
                                or reselecting the current group.
* Crosspost Handling::          How crossposted articles are dealt with.
* Duplicate Suppression::       An alternative when crosspost handling fails.
* Security::                    Decrypt and Verify.
* Mailing List::                Mailing list minor mode.
@end menu


@node Summary Buffer Format
@section Summary Buffer Format
@cindex summary buffer format

@iftex
@iflatex
\gnusfigure{The Summary Buffer}{180}{
\put(0,0){\epsfig{figure=ps/summary,width=7.5cm}}
\put(445,0){\makebox(0,0)[br]{\epsfig{figure=ps/summary-article,width=7.5cm}}}
}
@end iflatex
@end iftex

@menu
* Summary Buffer Lines::        You can specify how summary lines should look.
* To From Newsgroups::          How to not display your own name.
* Summary Buffer Mode Line::    You can say how the mode line should look.
* Summary Highlighting::        Making the summary buffer all pretty and nice.
@end menu

@findex mail-extract-address-components
@findex gnus-extract-address-components
@vindex gnus-extract-address-components
Gnus will use the value of the @code{gnus-extract-address-components}
variable as a function for getting the name and address parts of a
@code{From} header.  Two pre-defined functions exist:
@code{gnus-extract-address-components}, which is the default, quite
fast, and too simplistic solution; and
@code{mail-extract-address-components}, which works very nicely, but is
slower.  The default function will return the wrong answer in 5% of the
cases.  If this is unacceptable to you, use the other function instead:

@lisp
(setq gnus-extract-address-components
      'mail-extract-address-components)
@end lisp

@vindex gnus-summary-same-subject
@code{gnus-summary-same-subject} is a string indicating that the current
article has the same subject as the previous.  This string will be used
with those specs that require it.  The default is @code{""}.


@node Summary Buffer Lines
@subsection Summary Buffer Lines

@vindex gnus-summary-line-format
You can change the format of the lines in the summary buffer by changing
the @code{gnus-summary-line-format} variable.  It works along the same
lines as a normal @code{format} string, with some extensions
(@pxref{Formatting Variables}).

There should always be a colon or a point position marker on the line;
the cursor always moves to the point position marker or the colon after
performing an operation.  (Of course, Gnus wouldn't be Gnus if it wasn't
possible to change this.  Just write a new function
@code{gnus-goto-colon} which does whatever you like with the cursor.)
@xref{Positioning Point}.

The default string is @samp{%U%R%z%I%(%[%4L: %-23,23f%]%) %s\n}.

The following format specification characters and extended format
specification(s) are understood:

@table @samp
@item N
Article number.
@item S
Subject string.  List identifiers stripped,
@code{gnus-list-identifiers}.  @xref{Article Hiding}.
@item s
Subject if the article is the root of the thread or the previous article
had a different subject, @code{gnus-summary-same-subject} otherwise.
(@code{gnus-summary-same-subject} defaults to @code{""}.)
@item F
Full @code{From} header.
@item n
The name (from the @code{From} header).
@item f
The name, @code{To} header or the @code{Newsgroups} header (@pxref{To
From Newsgroups}).
@item a
The name (from the @code{From} header).  This differs from the @code{n}
spec in that it uses the function designated by the
@code{gnus-extract-address-components} variable, which is slower, but
may be more thorough.
@item A
The address (from the @code{From} header).  This works the same way as
the @code{a} spec.
@item L
Number of lines in the article.
@item c
Number of characters in the article.  This specifier is not supported
in some methods (like nnfolder).
@item k
Pretty-printed version of the number of characters in the article;
for example, @samp{1.2k} or @samp{0.4M}.
@item I
Indentation based on thread level (@pxref{Customizing Threading}).
@item B
A complex trn-style thread tree, showing response-connecting trace
lines.  A thread could be drawn like this:

@example
>
+->
| +->
| | \->
| |   \->
| \->
+->
\->
@end example

You can customize the appearance with the following options.  Note
that it is possible to make the thread display look really neat by
replacing the default @acronym{ASCII} characters with graphic
line-drawing glyphs.
@table @code
@item gnus-sum-thread-tree-root
@vindex gnus-sum-thread-tree-root
Used for the root of a thread.  If @code{nil}, use subject
instead.  The default is @samp{> }.

@item gnus-sum-thread-tree-false-root
@vindex gnus-sum-thread-tree-false-root
Used for the false root of a thread (@pxref{Loose Threads}).  If
@code{nil}, use subject instead.  The default is @samp{> }.

@item gnus-sum-thread-tree-single-indent
@vindex gnus-sum-thread-tree-single-indent
Used for a thread with just one message.  If @code{nil}, use subject
instead.  The default is @samp{}.

@item gnus-sum-thread-tree-vertical
@vindex gnus-sum-thread-tree-vertical
Used for drawing a vertical line.  The default is @samp{| }.

@item gnus-sum-thread-tree-indent
@vindex gnus-sum-thread-tree-indent
Used for indenting.  The default is @samp{  }.

@item gnus-sum-thread-tree-leaf-with-other
@vindex gnus-sum-thread-tree-leaf-with-other
Used for a leaf with brothers.  The default is @samp{+-> }.

@item gnus-sum-thread-tree-single-leaf
@vindex gnus-sum-thread-tree-single-leaf
Used for a leaf without brothers.  The default is @samp{\-> }

@end table

@item T
Nothing if the article is a root and lots of spaces if it isn't (it
pushes everything after it off the screen).
@item [
Opening bracket, which is normally @samp{[}, but can also be @samp{<}
for adopted articles (@pxref{Customizing Threading}).
@item ]
Closing bracket, which is normally @samp{]}, but can also be @samp{>}
for adopted articles.
@item >
One space for each thread level.
@item <
Twenty minus thread level spaces.
@item U
Unread.  @xref{Read Articles}.

@item R
This misleadingly named specifier is the @dfn{secondary mark}.  This
mark will say whether the article has been replied to, has been cached,
or has been saved.  @xref{Other Marks}.

@item i
Score as a number (@pxref{Scoring}).
@item z
@vindex gnus-summary-zcore-fuzz
Zcore, @samp{+} if above the default level and @samp{-} if below the
default level.  If the difference between
@code{gnus-summary-default-score} and the score is less than
@code{gnus-summary-zcore-fuzz}, this spec will not be used.
@item V
Total thread score.
@item x
@code{Xref}.
@item D
@code{Date}.
@item d
The @code{Date} in @code{DD-MMM} format.
@item o
The @code{Date} in @var{YYYYMMDD}@code{T}@var{HHMMSS} format.
@item M
@code{Message-ID}.
@item r
@code{References}.
@item t
Number of articles in the current sub-thread.  Using this spec will slow
down summary buffer generation somewhat.
@item e
An @samp{=} (@code{gnus-not-empty-thread-mark}) will be displayed if the
article has any children.
@item P
The line number.
@item O
Download mark.
@item *
Desired cursor position (instead of after first colon).
@item &user-date;
Age sensitive date format.  Various date format is defined in
@code{gnus-user-date-format-alist}.
@item u
User defined specifier.  The next character in the format string should
be a letter.  Gnus will call the function
@code{gnus-user-format-function-@var{x}}, where @var{x} is the letter
following @samp{%u}.  The function will be passed the current header as
argument.  The function should return a string, which will be inserted
into the summary just like information from any other summary specifier.
@end table

Text between @samp{%(} and @samp{%)} will be highlighted with
@code{gnus-mouse-face} when the mouse point is placed inside the area.
There can only be one such area.

The @samp{%U} (status), @samp{%R} (replied) and @samp{%z} (zcore) specs
have to be handled with care.  For reasons of efficiency, Gnus will
compute what column these characters will end up in, and ``hard-code''
that.  This means that it is invalid to have these specs after a
variable-length spec.  Well, you might not be arrested, but your summary
buffer will look strange, which is bad enough.

The smart choice is to have these specs as far to the left as possible.
(Isn't that the case with everything, though?  But I digress.)

This restriction may disappear in later versions of Gnus.


@node To From Newsgroups
@subsection To From Newsgroups
@cindex To
@cindex Newsgroups

In some groups (particularly in archive groups), the @code{From} header
isn't very interesting, since all the articles there are written by
you.  To display the information in the @code{To} or @code{Newsgroups}
headers instead, you need to decide three things: What information to
gather; where to display it; and when to display it.

@enumerate
@item
@vindex gnus-extra-headers
The reading of extra header information is controlled by the
@code{gnus-extra-headers}.  This is a list of header symbols.  For
instance:

@lisp
(setq gnus-extra-headers
      '(To Newsgroups X-Newsreader))
@end lisp

This will result in Gnus trying to obtain these three headers, and
storing it in header structures for later easy retrieval.

@item
@findex gnus-extra-header
The value of these extra headers can be accessed via the
@code{gnus-extra-header} function.  Here's a format line spec that will
access the @code{X-Newsreader} header:

@example
"%~(form (gnus-extra-header 'X-Newsreader))@@"
@end example

@item
@vindex gnus-ignored-from-addresses
The @code{gnus-ignored-from-addresses} variable says when the @samp{%f}
summary line spec returns the @code{To}, @code{Newsreader} or
@code{From} header.  If this regexp matches the contents of the
@code{From} header, the value of the @code{To} or @code{Newsreader}
headers are used instead.

To distinguish regular articles from those where the @code{From} field
has been swapped, a string is prefixed to the @code{To} or
@code{Newsgroups} header in the summary line.  By default the string is
@samp{-> } for @code{To} and @samp{=> } for @code{Newsgroups}, you can
customize these strings with @code{gnus-summary-to-prefix} and
@code{gnus-summary-newsgroup-prefix}.

@end enumerate

@vindex nnmail-extra-headers
A related variable is @code{nnmail-extra-headers}, which controls when
to include extra headers when generating overview (@acronym{NOV}) files.
If you have old overview files, you should regenerate them after
changing this variable, by entering the server buffer using @kbd{^},
and then @kbd{g} on the appropriate mail server (e.g., nnml) to cause
regeneration.

@vindex gnus-summary-line-format
You also have to instruct Gnus to display the data by changing the
@code{%n} spec to the @code{%f} spec in the
@code{gnus-summary-line-format} variable.

In summary, you'd typically put something like the following in
@file{~/.gnus.el}:

@lisp
(setq gnus-extra-headers
      '(To Newsgroups))
(setq nnmail-extra-headers gnus-extra-headers)
(setq gnus-summary-line-format
      "%U%R%z%I%(%[%4L: %-23,23f%]%) %s\n")
(setq gnus-ignored-from-addresses
      "Your Name Here")
@end lisp

(The values listed above are the default values in Gnus.  Alter them
to fit your needs.)

A note for news server administrators, or for users who wish to try to
convince their news server administrator to provide some additional
support:

The above is mostly useful for mail groups, where you have control over
the @acronym{NOV} files that are created.  However, if you can persuade your
nntp admin to add (in the usual implementation, notably INN):

@example
Newsgroups:full
@end example

to the end of her @file{overview.fmt} file, then you can use that just
as you would the extra headers from the mail groups.


@node Summary Buffer Mode Line
@subsection Summary Buffer Mode Line

@vindex gnus-summary-mode-line-format
You can also change the format of the summary mode bar (@pxref{Mode Line
Formatting}).  Set @code{gnus-summary-mode-line-format} to whatever you
like.  The default is @samp{Gnus: %%b [%A] %Z}.

Here are the elements you can play with:

@table @samp
@item G
Group name.
@item p
Unprefixed group name.
@item A
Current article number.
@item z
Current article score.
@item V
Gnus version.
@item U
Number of unread articles in this group.
@item e
Number of unread articles in this group that aren't displayed in the
summary buffer.
@item Z
A string with the number of unread and unselected articles represented
either as @samp{<%U(+%e) more>} if there are both unread and unselected
articles, and just as @samp{<%U more>} if there are just unread articles
and no unselected ones.
@item g
Shortish group name.  For instance, @samp{rec.arts.anime} will be
shortened to @samp{r.a.anime}.
@item S
Subject of the current article.
@item u
User-defined spec (@pxref{User-Defined Specs}).
@item s
Name of the current score file (@pxref{Scoring}).
@item d
Number of dormant articles (@pxref{Unread Articles}).
@item t
Number of ticked articles (@pxref{Unread Articles}).
@item r
Number of articles that have been marked as read in this session.
@item E
Number of articles expunged by the score files.
@end table


@node Summary Highlighting
@subsection Summary Highlighting

@table @code

@item gnus-visual-mark-article-hook
@vindex gnus-visual-mark-article-hook
This hook is run after selecting an article.  It is meant to be used for
highlighting the article in some way.  It is not run if
@code{gnus-visual} is @code{nil}.

@item gnus-summary-update-hook
@vindex gnus-summary-update-hook
This hook is called when a summary line is changed.  It is not run if
@code{gnus-visual} is @code{nil}.

@item gnus-summary-selected-face
@vindex gnus-summary-selected-face
This is the face (or @dfn{font} as some people call it) used to
highlight the current article in the summary buffer.

@item gnus-summary-highlight
@vindex gnus-summary-highlight
Summary lines are highlighted according to this variable, which is a
list where the elements are of the format @code{(@var{form}
. @var{face})}.  If you would, for instance, like ticked articles to be
italic and high-scored articles to be bold, you could set this variable
to something like
@lisp
(((eq mark gnus-ticked-mark) . italic)
 ((> score default) . bold))
@end lisp
As you may have guessed, if @var{form} returns a non-@code{nil} value,
@var{face} will be applied to the line.
@end table


@node Summary Maneuvering
@section Summary Maneuvering
@cindex summary movement

All the straight movement commands understand the numeric prefix and
behave pretty much as you'd expect.

None of these commands select articles.

@table @kbd
@item G M-n
@itemx M-n
@kindex M-n (Summary)
@kindex G M-n (Summary)
@findex gnus-summary-next-unread-subject
Go to the next summary line of an unread article
(@code{gnus-summary-next-unread-subject}).

@item G M-p
@itemx M-p
@kindex M-p (Summary)
@kindex G M-p (Summary)
@findex gnus-summary-prev-unread-subject
Go to the previous summary line of an unread article
(@code{gnus-summary-prev-unread-subject}).

@item G g
@kindex G g (Summary)
@findex gnus-summary-goto-subject
Ask for an article number and then go to the summary line of that article
without displaying the article (@code{gnus-summary-goto-subject}).
@end table

If Gnus asks you to press a key to confirm going to the next group, you
can use the @kbd{C-n} and @kbd{C-p} keys to move around the group
buffer, searching for the next group to read without actually returning
to the group buffer.

Variables related to summary movement:

@table @code

@vindex gnus-auto-select-next
@item gnus-auto-select-next
If you issue one of the movement commands (like @kbd{n}) and there are
no more unread articles after the current one, Gnus will offer to go to
the next group.  If this variable is @code{t} and the next group is
empty, Gnus will exit summary mode and return to the group buffer.  If
this variable is neither @code{t} nor @code{nil}, Gnus will select the
next group with unread articles.  As a special case, if this variable
is @code{quietly}, Gnus will select the next group without asking for
confirmation.  If this variable is @code{almost-quietly}, the same
will happen only if you are located on the last article in the group.
Finally, if this variable is @code{slightly-quietly}, the @kbd{Z n}
command will go to the next group without confirmation.  Also
@pxref{Group Levels}.

@item gnus-auto-select-same
@vindex gnus-auto-select-same
If non-@code{nil}, all the movement commands will try to go to the next
article with the same subject as the current.  (@dfn{Same} here might
mean @dfn{roughly equal}.  See @code{gnus-summary-gather-subject-limit}
for details (@pxref{Customizing Threading}).)  If there are no more
articles with the same subject, go to the first unread article.

This variable is not particularly useful if you use a threaded display.

@item gnus-summary-check-current
@vindex gnus-summary-check-current
If non-@code{nil}, all the ``unread'' movement commands will not proceed
to the next (or previous) article if the current article is unread.
Instead, they will choose the current article.

@item gnus-auto-center-summary
@vindex gnus-auto-center-summary
If non-@code{nil}, Gnus will keep the point in the summary buffer
centered at all times.  This makes things quite tidy, but if you have a
slow network connection, or simply do not like this un-Emacsism, you can
set this variable to @code{nil} to get the normal Emacs scrolling
action.  This will also inhibit horizontal re-centering of the summary
buffer, which might make it more inconvenient to read extremely long
threads.

This variable can also be a number.  In that case, center the window at
the given number of lines from the top.

@item gnus-summary-stop-at-end-of-message
@vindex gnus-summary-stop-at-end-of-message
If non-@code{nil}, don't go to the next article when hitting
@kbd{SPC}, and you're at the end of the article.

@end table


@node Choosing Articles
@section Choosing Articles
@cindex selecting articles

@menu
* Choosing Commands::           Commands for choosing articles.
* Choosing Variables::          Variables that influence these commands.
@end menu


@node Choosing Commands
@subsection Choosing Commands

None of the following movement commands understand the numeric prefix,
and they all select and display an article.

If you want to fetch new articles or redisplay the group, see
@ref{Exiting the Summary Buffer}.

@table @kbd
@item SPACE
@kindex SPACE (Summary)
@findex gnus-summary-next-page
Select the current article, or, if that one's read already, the next
unread article (@code{gnus-summary-next-page}).

If you have an article window open already and you press @kbd{SPACE}
again, the article will be scrolled.  This lets you conveniently
@kbd{SPACE} through an entire newsgroup.  @xref{Paging the Article}.

@item G n
@itemx n
@kindex n (Summary)
@kindex G n (Summary)
@findex gnus-summary-next-unread-article
@c @icon{gnus-summary-next-unread}
Go to next unread article (@code{gnus-summary-next-unread-article}).

@item G p
@itemx p
@kindex p (Summary)
@findex gnus-summary-prev-unread-article
@c @icon{gnus-summary-prev-unread}
Go to previous unread article (@code{gnus-summary-prev-unread-article}).

@item G N
@itemx N
@kindex N (Summary)
@kindex G N (Summary)
@findex gnus-summary-next-article
Go to the next article (@code{gnus-summary-next-article}).

@item G P
@itemx P
@kindex P (Summary)
@kindex G P (Summary)
@findex gnus-summary-prev-article
Go to the previous article (@code{gnus-summary-prev-article}).

@item G C-n
@kindex G C-n (Summary)
@findex gnus-summary-next-same-subject
Go to the next article with the same subject
(@code{gnus-summary-next-same-subject}).

@item G C-p
@kindex G C-p (Summary)
@findex gnus-summary-prev-same-subject
Go to the previous article with the same subject
(@code{gnus-summary-prev-same-subject}).

@item G f
@itemx .
@kindex G f  (Summary)
@kindex .  (Summary)
@findex gnus-summary-first-unread-article
Go to the first unread article
(@code{gnus-summary-first-unread-article}).

@item G b
@itemx ,
@kindex G b (Summary)
@kindex , (Summary)
@findex gnus-summary-best-unread-article
Go to the unread article with the highest score
(@code{gnus-summary-best-unread-article}).  If given a prefix argument,
go to the first unread article that has a score over the default score.

@item G l
@itemx l
@kindex l (Summary)
@kindex G l (Summary)
@findex gnus-summary-goto-last-article
Go to the previous article read (@code{gnus-summary-goto-last-article}).

@item G o
@kindex G o (Summary)
@findex gnus-summary-pop-article
@cindex history
@cindex article history
Pop an article off the summary history and go to this article
(@code{gnus-summary-pop-article}).  This command differs from the
command above in that you can pop as many previous articles off the
history as you like, while @kbd{l} toggles the two last read articles.
For a somewhat related issue (if you use these commands a lot),
@pxref{Article Backlog}.

@item G j
@itemx j
@kindex j (Summary)
@kindex G j (Summary)
@findex gnus-summary-goto-article
Ask for an article number or @code{Message-ID}, and then go to that
article (@code{gnus-summary-goto-article}).

@end table


@node Choosing Variables
@subsection Choosing Variables

Some variables relevant for moving and selecting articles:

@table @code
@item gnus-auto-extend-newsgroup
@vindex gnus-auto-extend-newsgroup
All the movement commands will try to go to the previous (or next)
article, even if that article isn't displayed in the Summary buffer if
this variable is non-@code{nil}.  Gnus will then fetch the article from
the server and display it in the article buffer.

@item gnus-select-article-hook
@vindex gnus-select-article-hook
This hook is called whenever an article is selected.  The default is
@code{nil}.  If you would like each article to be saved in the Agent as
you read it, putting @code{gnus-agent-fetch-selected-article} on this
hook will do so.

@item gnus-mark-article-hook
@vindex gnus-mark-article-hook
@findex gnus-summary-mark-unread-as-read
@findex gnus-summary-mark-read-and-unread-as-read
@findex gnus-unread-mark
This hook is called whenever an article is selected.  It is intended to
be used for marking articles as read.  The default value is
@code{gnus-summary-mark-read-and-unread-as-read}, and will change the
mark of almost any article you read to @code{gnus-read-mark}.  The only
articles not affected by this function are ticked, dormant, and
expirable articles.  If you'd instead like to just have unread articles
marked as read, you can use @code{gnus-summary-mark-unread-as-read}
instead.  It will leave marks like @code{gnus-low-score-mark},
@code{gnus-del-mark} (and so on) alone.

@end table


@node Paging the Article
@section Scrolling the Article
@cindex article scrolling

@table @kbd

@item SPACE
@kindex SPACE (Summary)
@findex gnus-summary-next-page
Pressing @kbd{SPACE} will scroll the current article forward one page,
or, if you have come to the end of the current article, will choose the
next article (@code{gnus-summary-next-page}).

@vindex gnus-article-boring-faces
@vindex gnus-article-skip-boring
If @code{gnus-article-skip-boring} is non-@code{nil} and the rest of
the article consists only of citations and signature, then it will be
skipped; the next article will be shown instead.  You can customize
what is considered uninteresting with
@code{gnus-article-boring-faces}.  You can manually view the article's
pages, no matter how boring, using @kbd{C-M-v}.

@item DEL
@kindex DEL (Summary)
@findex gnus-summary-prev-page
Scroll the current article back one page (@code{gnus-summary-prev-page}).

@item RET
@kindex RET (Summary)
@findex gnus-summary-scroll-up
Scroll the current article one line forward
(@code{gnus-summary-scroll-up}).

@item M-RET
@kindex M-RET (Summary)
@findex gnus-summary-scroll-down
Scroll the current article one line backward
(@code{gnus-summary-scroll-down}).

@item A g
@itemx g
@kindex A g (Summary)
@kindex g (Summary)
@findex gnus-summary-show-article
@vindex gnus-summary-show-article-charset-alist
(Re)fetch the current article (@code{gnus-summary-show-article}).  If
given a prefix, show a completely ``raw'' article, just the way it
came from the server.  If given a prefix twice (i.e., @kbd{C-u C-u
g'}), fetch the current article, but don't run any of the article
treatment functions.

@cindex charset, view article with different charset
If given a numerical prefix, you can do semi-manual charset stuff.
@kbd{C-u 0 g cn-gb-2312 RET} will decode the message as if it were
encoded in the @code{cn-gb-2312} charset.  If you have

@lisp
(setq gnus-summary-show-article-charset-alist
      '((1 . cn-gb-2312)
        (2 . big5)))
@end lisp

then you can say @kbd{C-u 1 g} to get the same effect.

@item A <
@itemx <
@kindex < (Summary)
@kindex A < (Summary)
@findex gnus-summary-beginning-of-article
Scroll to the beginning of the article
(@code{gnus-summary-beginning-of-article}).

@item A >
@itemx >
@kindex > (Summary)
@kindex A > (Summary)
@findex gnus-summary-end-of-article
Scroll to the end of the article (@code{gnus-summary-end-of-article}).

@item A s
@itemx s
@kindex A s (Summary)
@kindex s (Summary)
@findex gnus-summary-isearch-article
Perform an isearch in the article buffer
(@code{gnus-summary-isearch-article}).

@item h
@kindex h (Summary)
@findex gnus-summary-select-article-buffer
Select the article buffer (@code{gnus-summary-select-article-buffer}).

@end table


@node Reply Followup and Post
@section Reply, Followup and Post

@menu
* Summary Mail Commands::       Sending mail.
* Summary Post Commands::       Sending news.
* Summary Message Commands::    Other Message-related commands.
* Canceling and Superseding::
@end menu


@node Summary Mail Commands
@subsection Summary Mail Commands
@cindex mail
@cindex composing mail

Commands for composing a mail message:

@table @kbd

@item S r
@itemx r
@kindex S r (Summary)
@kindex r (Summary)
@findex gnus-summary-reply
@c @icon{gnus-summary-mail-reply}
@c @icon{gnus-summary-reply}
Mail a reply to the author of the current article
(@code{gnus-summary-reply}).

@item S R
@itemx R
@kindex R (Summary)
@kindex S R (Summary)
@findex gnus-summary-reply-with-original
@c @icon{gnus-summary-reply-with-original}
Mail a reply to the author of the current article and include the
original message (@code{gnus-summary-reply-with-original}).  This
command uses the process/prefix convention.

@item S w
@kindex S w (Summary)
@findex gnus-summary-wide-reply
Mail a wide reply to the author of the current article
(@code{gnus-summary-wide-reply}).  A @dfn{wide reply} is a reply that
goes out to all people listed in the @code{To}, @code{From} (or
@code{Reply-to}) and @code{Cc} headers.  If @code{Mail-Followup-To} is
present, that's used instead.

@item S W
@kindex S W (Summary)
@findex gnus-summary-wide-reply-with-original
Mail a wide reply to the current article and include the original
message (@code{gnus-summary-wide-reply-with-original}).  This command uses
the process/prefix convention, but only uses the headers from the
first article to determine the recipients.

@item S L
@kindex S L (Summary)
@findex gnus-summary-reply-to-list-with-original
When replying to a message from a mailing list, send a reply to that
message to the mailing list, and include the original message
(@code{gnus-summary-reply-to-list-with-original}).

@item S v
@kindex S v (Summary)
@findex gnus-summary-very-wide-reply
Mail a very wide reply to the author of the current article
(@code{gnus-summary-wide-reply}).  A @dfn{very wide reply} is a reply
that goes out to all people listed in the @code{To}, @code{From} (or
@code{Reply-to}) and @code{Cc} headers in all the process/prefixed
articles.  This command uses the process/prefix convention.

@item S V
@kindex S V (Summary)
@findex gnus-summary-very-wide-reply-with-original
Mail a very wide reply to the author of the current article and include the
original message (@code{gnus-summary-very-wide-reply-with-original}).  This
command uses the process/prefix convention.

@item S B r
@kindex S B r (Summary)
@findex gnus-summary-reply-broken-reply-to
Mail a reply to the author of the current article but ignore the
@code{Reply-To} field (@code{gnus-summary-reply-broken-reply-to}).
If you need this because a mailing list incorrectly sets a
@code{Reply-To} header pointing to the list, you probably want to set
the @code{broken-reply-to} group parameter instead, so things will work
correctly.  @xref{Group Parameters}.

@item S B R
@kindex S B R (Summary)
@findex gnus-summary-reply-broken-reply-to-with-original
Mail a reply to the author of the current article and include the
original message but ignore the @code{Reply-To} field
(@code{gnus-summary-reply-broken-reply-to-with-original}).

@item S o m
@itemx C-c C-f
@kindex S o m (Summary)
@kindex C-c C-f (Summary)
@findex gnus-summary-mail-forward
@c @icon{gnus-summary-mail-forward}
Forward the current article to some other person
(@code{gnus-summary-mail-forward}).  If no prefix is given, the message
is forwarded according to the value of (@code{message-forward-as-mime})
and (@code{message-forward-show-mml}); if the prefix is 1, decode the
message and forward directly inline; if the prefix is 2, forward message
as an rfc822 @acronym{MIME} section; if the prefix is 3, decode message and
forward as an rfc822 @acronym{MIME} section; if the prefix is 4, forward message
directly inline; otherwise, the message is forwarded as no prefix given
but use the flipped value of (@code{message-forward-as-mime}).  By
default, the message is decoded and forwarded as an rfc822 @acronym{MIME}
section.

@item S m
@itemx m
@kindex m (Summary)
@kindex S m (Summary)
@findex gnus-summary-mail-other-window
@c @icon{gnus-summary-mail-originate}
Prepare a mail (@code{gnus-summary-mail-other-window}).  By default, use
the posting style of the current group.  If given a prefix, disable that.
If the prefix is 1, prompt for a group name to find the posting style.

@item S i
@kindex S i (Summary)
@findex gnus-summary-news-other-window
Prepare a news (@code{gnus-summary-news-other-window}).  By default,
post to the current group.  If given a prefix, disable that.  If the
prefix is 1, prompt for a group to post to.

This function actually prepares a news even when using mail groups.
This is useful for ``posting'' messages to mail groups without actually
sending them over the network: they're just saved directly to the group
in question.  The corresponding back end must have a request-post method
for this to work though.

@item S D b
@kindex S D b (Summary)
@findex gnus-summary-resend-bounced-mail
@cindex bouncing mail
If you have sent a mail, but the mail was bounced back to you for some
reason (wrong address, transient failure), you can use this command to
resend that bounced mail (@code{gnus-summary-resend-bounced-mail}).  You
will be popped into a mail buffer where you can edit the headers before
sending the mail off again.  If you give a prefix to this command, and
the bounced mail is a reply to some other mail, Gnus will try to fetch
that mail and display it for easy perusal of its headers.  This might
very well fail, though.

@item S D r
@kindex S D r (Summary)
@findex gnus-summary-resend-message
Not to be confused with the previous command,
@code{gnus-summary-resend-message} will prompt you for an address to
send the current message off to, and then send it to that place.  The
headers of the message won't be altered---but lots of headers that say
@code{Resent-To}, @code{Resent-From} and so on will be added.  This
means that you actually send a mail to someone that has a @code{To}
header that (probably) points to yourself.  This will confuse people.
So, natcherly you'll only do that if you're really eVIl.

This command is mainly used if you have several accounts and want to
ship a mail to a different account of yours.  (If you're both
@code{root} and @code{postmaster} and get a mail for @code{postmaster}
to the @code{root} account, you may want to resend it to
@code{postmaster}.  Ordnung muss sein!

This command understands the process/prefix convention
(@pxref{Process/Prefix}).

@item S D e
@kindex S D e (Summary)
@findex gnus-summary-resend-message-edit

Like the previous command, but will allow you to edit the message as
if it were a new message before resending.

@item S O m
@kindex S O m (Summary)
@findex gnus-uu-digest-mail-forward
Digest the current series (@pxref{Decoding Articles}) and forward the
result using mail (@code{gnus-uu-digest-mail-forward}).  This command
uses the process/prefix convention (@pxref{Process/Prefix}).

@item S M-c
@kindex S M-c (Summary)
@findex gnus-summary-mail-crosspost-complaint
@cindex crossposting
@cindex excessive crossposting
Send a complaint about excessive crossposting to the author of the
current article (@code{gnus-summary-mail-crosspost-complaint}).

@findex gnus-crosspost-complaint
This command is provided as a way to fight back against the current
crossposting pandemic that's sweeping Usenet.  It will compose a reply
using the @code{gnus-crosspost-complaint} variable as a preamble.  This
command understands the process/prefix convention
(@pxref{Process/Prefix}) and will prompt you before sending each mail.

@end table

Also @xref{Header Commands, ,Header Commands, message, The Message
Manual}, for more information.


@node Summary Post Commands
@subsection Summary Post Commands
@cindex post
@cindex composing news

Commands for posting a news article:

@table @kbd
@item S p
@itemx a
@kindex a (Summary)
@kindex S p (Summary)
@findex gnus-summary-post-news
@c @icon{gnus-summary-post-news}
Prepare for posting an article (@code{gnus-summary-post-news}).  By
default, post to the current group.  If given a prefix, disable that.
If the prefix is 1, prompt for another group instead.

@item S f
@itemx f
@kindex f (Summary)
@kindex S f (Summary)
@findex gnus-summary-followup
@c @icon{gnus-summary-followup}
Post a followup to the current article (@code{gnus-summary-followup}).

@item S F
@itemx F
@kindex S F (Summary)
@kindex F (Summary)
@c @icon{gnus-summary-followup-with-original}
@findex gnus-summary-followup-with-original
Post a followup to the current article and include the original message
(@code{gnus-summary-followup-with-original}).  This command uses the
process/prefix convention.

@item S n
@kindex S n (Summary)
@findex gnus-summary-followup-to-mail
Post a followup to the current article via news, even if you got the
message through mail (@code{gnus-summary-followup-to-mail}).

@item S N
@kindex S N (Summary)
@findex gnus-summary-followup-to-mail-with-original
Post a followup to the current article via news, even if you got the
message through mail and include the original message
(@code{gnus-summary-followup-to-mail-with-original}).  This command uses
the process/prefix convention.

@item S o p
@kindex S o p (Summary)
@findex gnus-summary-post-forward
Forward the current article to a newsgroup
(@code{gnus-summary-post-forward}).
 If no prefix is given, the message is forwarded according to the value
of (@code{message-forward-as-mime}) and
(@code{message-forward-show-mml}); if the prefix is 1, decode the
message and forward directly inline; if the prefix is 2, forward message
as an rfc822 @acronym{MIME} section; if the prefix is 3, decode message and
forward as an rfc822 @acronym{MIME} section; if the prefix is 4, forward message
directly inline; otherwise, the message is forwarded as no prefix given
but use the flipped value of (@code{message-forward-as-mime}).  By
default, the message is decoded and forwarded as an rfc822 @acronym{MIME} section.

@item S O p
@kindex S O p (Summary)
@findex gnus-uu-digest-post-forward
@cindex digests
@cindex making digests
Digest the current series and forward the result to a newsgroup
(@code{gnus-uu-digest-post-forward}).  This command uses the
process/prefix convention.

@item S u
@kindex S u (Summary)
@findex gnus-uu-post-news
@c @icon{gnus-uu-post-news}
Uuencode a file, split it into parts, and post it as a series
(@code{gnus-uu-post-news}).  (@pxref{Uuencoding and Posting}).
@end table

Also @xref{Header Commands, ,Header Commands, message, The Message
Manual}, for more information.


@node Summary Message Commands
@subsection Summary Message Commands

@table @kbd
@item S y
@kindex S y (Summary)
@findex gnus-summary-yank-message
Yank the current article into an already existing Message composition
buffer (@code{gnus-summary-yank-message}).  This command prompts for
what message buffer you want to yank into, and understands the
process/prefix convention (@pxref{Process/Prefix}).

@end table


@node Canceling and Superseding
@subsection Canceling Articles
@cindex canceling articles
@cindex superseding articles

Have you ever written something, and then decided that you really,
really, really wish you hadn't posted that?

Well, you can't cancel mail, but you can cancel posts.

@findex gnus-summary-cancel-article
@kindex C (Summary)
@c @icon{gnus-summary-cancel-article}
Find the article you wish to cancel (you can only cancel your own
articles, so don't try any funny stuff).  Then press @kbd{C} or @kbd{S
c} (@code{gnus-summary-cancel-article}).  Your article will be
canceled---machines all over the world will be deleting your article.
This command uses the process/prefix convention (@pxref{Process/Prefix}).

Be aware, however, that not all sites honor cancels, so your article may
live on here and there, while most sites will delete the article in
question.

Gnus will use the ``current'' select method when canceling.  If you
want to use the standard posting method, use the @samp{a} symbolic
prefix (@pxref{Symbolic Prefixes}).

Gnus ensures that only you can cancel your own messages using a
@code{Cancel-Lock} header (@pxref{Canceling News, Canceling News, ,
message, Message Manual}).

If you discover that you have made some mistakes and want to do some
corrections, you can post a @dfn{superseding} article that will replace
your original article.

@findex gnus-summary-supersede-article
@kindex S (Summary)
Go to the original article and press @kbd{S s}
(@code{gnus-summary-supersede-article}).  You will be put in a buffer
where you can edit the article all you want before sending it off the
usual way.

The same goes for superseding as for canceling, only more so: Some
sites do not honor superseding.  On those sites, it will appear that you
have posted almost the same article twice.

If you have just posted the article, and change your mind right away,
there is a trick you can use to cancel/supersede the article without
waiting for the article to appear on your site first.  You simply return
to the post buffer (which is called @code{*sent ...*}).  There you will
find the article you just posted, with all the headers intact.  Change
the @code{Message-ID} header to a @code{Cancel} or @code{Supersedes}
header by substituting one of those words for the word
@code{Message-ID}.  Then just press @kbd{C-c C-c} to send the article as
you would do normally.  The previous article will be
canceled/superseded.

Just remember, kids: There is no 'c' in 'supersede'.

@node Delayed Articles
@section Delayed Articles
@cindex delayed sending
@cindex send delayed

Sometimes, you might wish to delay the sending of a message.  For
example, you might wish to arrange for a message to turn up just in time
to remind your about the birthday of your Significant Other.  For this,
there is the @code{gnus-delay} package.  Setup is simple:

@lisp
(gnus-delay-initialize)
@end lisp

@findex gnus-delay-article
Normally, to send a message you use the @kbd{C-c C-c} command from
Message mode.  To delay a message, use @kbd{C-c C-j}
(@code{gnus-delay-article}) instead.  This will ask you for how long the
message should be delayed.  Possible answers are:

@itemize @bullet
@item
A time span.  Consists of an integer and a letter.  For example,
@code{42d} means to delay for 42 days.  Available letters are @code{m}
(minutes), @code{h} (hours), @code{d} (days), @code{w} (weeks), @code{M}
(months) and @code{Y} (years).

@item
A specific date.  Looks like @code{YYYY-MM-DD}.  The message will be
delayed until that day, at a specific time (eight o'clock by default).
See also @code{gnus-delay-default-hour}.

@item
A specific time of day.  Given in @code{hh:mm} format, 24h, no am/pm
stuff.  The deadline will be at that time today, except if that time has
already passed, then it's at the given time tomorrow.  So if it's ten
o'clock in the morning and you specify @code{11:15}, then the deadline
is one hour and fifteen minutes hence.  But if you specify @code{9:20},
that means a time tomorrow.
@end itemize

The action of the @code{gnus-delay-article} command is influenced by a
couple of variables:

@table @code
@item gnus-delay-default-hour
@vindex gnus-delay-default-hour
When you specify a specific date, the message will be due on that hour
on the given date.  Possible values are integers 0 through 23.

@item gnus-delay-default-delay
@vindex gnus-delay-default-delay
This is a string and gives the default delay.  It can be of any of the
formats described above.

@item gnus-delay-group
@vindex gnus-delay-group
Delayed articles will be kept in this group on the drafts server until
they are due.  You probably don't need to change this.  The default
value is @code{"delayed"}.

@item gnus-delay-header
@vindex gnus-delay-header
The deadline for each article will be stored in a header.  This variable
is a string and gives the header name.  You probably don't need to
change this.  The default value is @code{"X-Gnus-Delayed"}.
@end table

The way delaying works is like this: when you use the
@code{gnus-delay-article} command, you give a certain delay.  Gnus
calculates the deadline of the message and stores it in the
@code{X-Gnus-Delayed} header and puts the message in the
@code{nndraft:delayed} group.

@findex gnus-delay-send-queue
And whenever you get new news, Gnus looks through the group for articles
which are due and sends them.  It uses the @code{gnus-delay-send-queue}
function for this.  By default, this function is added to the hook
@code{gnus-get-new-news-hook}.  But of course, you can change this.
Maybe you want to use the demon to send drafts?  Just tell the demon to
execute the @code{gnus-delay-send-queue} function.

@table @code
@item gnus-delay-initialize
@findex gnus-delay-initialize
By default, this function installs @code{gnus-delay-send-queue} in
@code{gnus-get-new-news-hook}.  But it accepts the optional second
argument @code{no-check}.  If it is non-@code{nil},
@code{gnus-get-new-news-hook} is not changed.  The optional first
argument is ignored.

For example, @code{(gnus-delay-initialize nil t)} means to do nothing.
Presumably, you want to use the demon for sending due delayed articles.
Just don't forget to set that up :-)
@end table

When delaying an article with @kbd{C-c C-j}, Message mode will
automatically add a @code{"Date"} header with the current time.  In
many cases you probably want the @code{"Date"} header to reflect the
time the message is sent instead.  To do this, you have to delete
@code{Date} from @code{message-draft-headers}.


@node Marking Articles
@section Marking Articles
@cindex article marking
@cindex article ticking
@cindex marks

There are several marks you can set on an article.

You have marks that decide the @dfn{readedness} (whoo, neato-keano
neologism ohoy!) of the article.  Alphabetic marks generally mean
@dfn{read}, while non-alphabetic characters generally mean @dfn{unread}.

In addition, you also have marks that do not affect readedness.

@ifinfo
There's a plethora of commands for manipulating these marks.
@end ifinfo

@menu
* Unread Articles::             Marks for unread articles.
* Read Articles::               Marks for read articles.
* Other Marks::                 Marks that do not affect readedness.
* Setting Marks::               How to set and remove marks.
* Generic Marking Commands::    How to customize the marking.
* Setting Process Marks::       How to mark articles for later processing.
@end menu


@node Unread Articles
@subsection Unread Articles

The following marks mark articles as (kinda) unread, in one form or
other.

@table @samp
@item !
@vindex gnus-ticked-mark
Marked as ticked (@code{gnus-ticked-mark}).

@dfn{Ticked articles} are articles that will remain visible always.  If
you see an article that you find interesting, or you want to put off
reading it, or replying to it, until sometime later, you'd typically
tick it.  However, articles can be expired (from news servers by the
news server software, Gnus itself never expires ticked messages), so if
you want to keep an article forever, you'll have to make it persistent
(@pxref{Persistent Articles}).

@item ?
@vindex gnus-dormant-mark
Marked as dormant (@code{gnus-dormant-mark}).

@dfn{Dormant articles} will only appear in the summary buffer if there
are followups to it.  If you want to see them even if they don't have
followups, you can use the @kbd{/ D} command (@pxref{Limiting}).
Otherwise (except for the visibility issue), they are just like ticked
messages.

@item SPACE
@vindex gnus-unread-mark
Marked as unread (@code{gnus-unread-mark}).

@dfn{Unread articles} are articles that haven't been read at all yet.
@end table


@node Read Articles
@subsection Read Articles
@cindex expirable mark

All the following marks mark articles as read.

@table @samp

@item r
@vindex gnus-del-mark
These are articles that the user has marked as read with the @kbd{d}
command manually, more or less (@code{gnus-del-mark}).

@item R
@vindex gnus-read-mark
Articles that have actually been read (@code{gnus-read-mark}).

@item O
@vindex gnus-ancient-mark
Articles that were marked as read in previous sessions and are now
@dfn{old} (@code{gnus-ancient-mark}).

@item K
@vindex gnus-killed-mark
Marked as killed (@code{gnus-killed-mark}).

@item X
@vindex gnus-kill-file-mark
Marked as killed by kill files (@code{gnus-kill-file-mark}).

@item Y
@vindex gnus-low-score-mark
Marked as read by having too low a score (@code{gnus-low-score-mark}).

@item C
@vindex gnus-catchup-mark
Marked as read by a catchup (@code{gnus-catchup-mark}).

@item G
@vindex gnus-canceled-mark
Canceled article (@code{gnus-canceled-mark})

@item Q
@vindex gnus-sparse-mark
Sparsely reffed article (@code{gnus-sparse-mark}).  @xref{Customizing
Threading}.

@item M
@vindex gnus-duplicate-mark
Article marked as read by duplicate suppression
(@code{gnus-duplicate-mark}).  @xref{Duplicate Suppression}.

@end table

All these marks just mean that the article is marked as read, really.
They are interpreted differently when doing adaptive scoring, though.

One more special mark, though:

@table @samp
@item E
@vindex gnus-expirable-mark
Marked as expirable (@code{gnus-expirable-mark}).

Marking articles as @dfn{expirable} (or have them marked as such
automatically) doesn't make much sense in normal groups---a user doesn't
control expiring of news articles, but in mail groups, for instance,
articles marked as @dfn{expirable} can be deleted by Gnus at
any time.
@end table


@node Other Marks
@subsection Other Marks
@cindex process mark
@cindex bookmarks

There are some marks that have nothing to do with whether the article is
read or not.

@itemize @bullet

@item
You can set a bookmark in the current article.  Say you are reading a
long thesis on cats' urinary tracts, and have to go home for dinner
before you've finished reading the thesis.  You can then set a bookmark
in the article, and Gnus will jump to this bookmark the next time it
encounters the article.  @xref{Setting Marks}.

@item
@vindex gnus-replied-mark
All articles that you have replied to or made a followup to (i.e., have
answered) will be marked with an @samp{A} in the second column
(@code{gnus-replied-mark}).

@item
@vindex gnus-forwarded-mark
All articles that you have forwarded will be marked with an @samp{F} in
the second column (@code{gnus-forwarded-mark}).

@item
@vindex gnus-cached-mark
Articles stored in the article cache will be marked with an @samp{*} in
the second column (@code{gnus-cached-mark}).  @xref{Article Caching}.

@item
@vindex gnus-saved-mark
Articles ``saved'' (in some manner or other; not necessarily
religiously) are marked with an @samp{S} in the second column
(@code{gnus-saved-mark}).

@item
@vindex gnus-unseen-mark
Articles that haven't been seen before in Gnus by the user are marked
with a @samp{.} in the second column (@code{gnus-unseen-mark}).

@item
@vindex gnus-downloaded-mark
When using the Gnus agent (@pxref{Agent Basics}), articles may be
downloaded for unplugged (offline) viewing.  If you are using the
@samp{%O} spec, these articles get the @samp{+} mark in that spec.
(The variable @code{gnus-downloaded-mark} controls which character to
use.)

@item
@vindex gnus-undownloaded-mark
When using the Gnus agent (@pxref{Agent Basics}), some articles might
not have been downloaded.  Such articles cannot be viewed while you
are unplugged (offline).  If you are using the @samp{%O} spec, these
articles get the @samp{-} mark in that spec.  (The variable
@code{gnus-undownloaded-mark} controls which character to use.)

@item
@vindex gnus-downloadable-mark
The Gnus agent (@pxref{Agent Basics}) downloads some articles
automatically, but it is also possible to explicitly mark articles for
download, even if they would not be downloaded automatically.  Such
explicitly-marked articles get the @samp{%} mark in the first column.
(The variable @code{gnus-downloadable-mark} controls which character to
use.)

@item
@vindex gnus-not-empty-thread-mark
@vindex gnus-empty-thread-mark
If the @samp{%e} spec is used, the presence of threads or not will be
marked with @code{gnus-not-empty-thread-mark} and
@code{gnus-empty-thread-mark} in the third column, respectively.

@item
@vindex gnus-process-mark
Finally we have the @dfn{process mark} (@code{gnus-process-mark}).  A
variety of commands react to the presence of the process mark.  For
instance, @kbd{X u} (@code{gnus-uu-decode-uu}) will uudecode and view
all articles that have been marked with the process mark.  Articles
marked with the process mark have a @samp{#} in the second column.

@end itemize

You might have noticed that most of these ``non-readedness'' marks
appear in the second column by default.  So if you have a cached, saved,
replied article that you have process-marked, what will that look like?

Nothing much.  The precedence rules go as follows: process -> cache ->
replied -> saved.  So if the article is in the cache and is replied,
you'll only see the cache mark and not the replied mark.


@node Setting Marks
@subsection Setting Marks
@cindex setting marks

All the marking commands understand the numeric prefix.

@table @kbd
@item M c
@itemx M-u
@kindex M c (Summary)
@kindex M-u (Summary)
@findex gnus-summary-clear-mark-forward
@cindex mark as unread
Clear all readedness-marks from the current article
(@code{gnus-summary-clear-mark-forward}).  In other words, mark the
article as unread.

@item M t
@itemx !
@kindex ! (Summary)
@kindex M t (Summary)
@findex gnus-summary-tick-article-forward
Tick the current article (@code{gnus-summary-tick-article-forward}).
@xref{Article Caching}.

@item M ?
@itemx ?
@kindex ? (Summary)
@kindex M ? (Summary)
@findex gnus-summary-mark-as-dormant
Mark the current article as dormant
(@code{gnus-summary-mark-as-dormant}).  @xref{Article Caching}.

@item M d
@itemx d
@kindex M d (Summary)
@kindex d (Summary)
@findex gnus-summary-mark-as-read-forward
Mark the current article as read
(@code{gnus-summary-mark-as-read-forward}).

@item D
@kindex D (Summary)
@findex gnus-summary-mark-as-read-backward
Mark the current article as read and move point to the previous line
(@code{gnus-summary-mark-as-read-backward}).

@item M k
@itemx k
@kindex k (Summary)
@kindex M k (Summary)
@findex gnus-summary-kill-same-subject-and-select
Mark all articles that have the same subject as the current one as read,
and then select the next unread article
(@code{gnus-summary-kill-same-subject-and-select}).

@item M K
@itemx C-k
@kindex M K (Summary)
@kindex C-k (Summary)
@findex gnus-summary-kill-same-subject
Mark all articles that have the same subject as the current one as read
(@code{gnus-summary-kill-same-subject}).

@item M C
@kindex M C (Summary)
@findex gnus-summary-catchup
@c @icon{gnus-summary-catchup}
Mark all unread articles as read (@code{gnus-summary-catchup}).

@item M C-c
@kindex M C-c (Summary)
@findex gnus-summary-catchup-all
Mark all articles in the group as read---even the ticked and dormant
articles (@code{gnus-summary-catchup-all}).

@item M H
@kindex M H (Summary)
@findex gnus-summary-catchup-to-here
Catchup the current group to point (before the point)
(@code{gnus-summary-catchup-to-here}).

@item M h
@kindex M h (Summary)
@findex gnus-summary-catchup-from-here
Catchup the current group from point (after the point)
(@code{gnus-summary-catchup-from-here}).

@item C-w
@kindex C-w (Summary)
@findex gnus-summary-mark-region-as-read
Mark all articles between point and mark as read
(@code{gnus-summary-mark-region-as-read}).

@item M V k
@kindex M V k (Summary)
@findex gnus-summary-kill-below
Kill all articles with scores below the default score (or below the
numeric prefix) (@code{gnus-summary-kill-below}).

@item M e
@itemx E
@kindex M e (Summary)
@kindex E (Summary)
@findex gnus-summary-mark-as-expirable
Mark the current article as expirable
(@code{gnus-summary-mark-as-expirable}).

@item M b
@kindex M b (Summary)
@findex gnus-summary-set-bookmark
Set a bookmark in the current article
(@code{gnus-summary-set-bookmark}).

@item M B
@kindex M B (Summary)
@findex gnus-summary-remove-bookmark
Remove the bookmark from the current article
(@code{gnus-summary-remove-bookmark}).

@item M V c
@kindex M V c (Summary)
@findex gnus-summary-clear-above
Clear all marks from articles with scores over the default score (or
over the numeric prefix) (@code{gnus-summary-clear-above}).

@item M V u
@kindex M V u (Summary)
@findex gnus-summary-tick-above
Tick all articles with scores over the default score (or over the
numeric prefix) (@code{gnus-summary-tick-above}).

@item M V m
@kindex M V m (Summary)
@findex gnus-summary-mark-above
Prompt for a mark, and mark all articles with scores over the default
score (or over the numeric prefix) with this mark
(@code{gnus-summary-clear-above}).
@end table

@vindex gnus-summary-goto-unread
The @code{gnus-summary-goto-unread} variable controls what action should
be taken after setting a mark.  If non-@code{nil}, point will move to
the next/previous unread article.  If @code{nil}, point will just move
one line up or down.  As a special case, if this variable is
@code{never}, all the marking commands as well as other commands (like
@kbd{SPACE}) will move to the next article, whether it is unread or not.
The default is @code{t}.


@node Generic Marking Commands
@subsection Generic Marking Commands

Some people would like the command that ticks an article (@kbd{!}) to
go to the next article.  Others would like it to go to the next unread
article.  Yet others would like it to stay on the current article.
And even though I haven't heard of anybody wanting it to go to the
previous (unread) article, I'm sure there are people that want that as
well.

Multiply these five behaviors with five different marking commands, and
you get a potentially complex set of variable to control what each
command should do.

To sidestep that mess, Gnus provides commands that do all these
different things.  They can be found on the @kbd{M M} map in the summary
buffer.  Type @kbd{M M C-h} to see them all---there are too many of them
to list in this manual.

While you can use these commands directly, most users would prefer
altering the summary mode keymap.  For instance, if you would like the
@kbd{!} command to go to the next article instead of the next unread
article, you could say something like:

@lisp
@group
(add-hook 'gnus-summary-mode-hook 'my-alter-summary-map)
(defun my-alter-summary-map ()
  (local-set-key "!" 'gnus-summary-put-mark-as-ticked-next))
@end group
@end lisp

@noindent
or

@lisp
(defun my-alter-summary-map ()
  (local-set-key "!" "MM!n"))
@end lisp


@node Setting Process Marks
@subsection Setting Process Marks
@cindex setting process marks

Process marks are displayed as @code{#} in the summary buffer, and are
used for marking articles in such a way that other commands will
process these articles.  For instance, if you process mark four
articles and then use the @kbd{*} command, Gnus will enter these four
articles into the cache.  For more information,
@pxref{Process/Prefix}.

@table @kbd

@item M P p
@itemx #
@kindex # (Summary)
@kindex M P p (Summary)
@findex gnus-summary-mark-as-processable
Mark the current article with the process mark
(@code{gnus-summary-mark-as-processable}).
@findex gnus-summary-unmark-as-processable

@item M P u
@itemx M-#
@kindex M P u (Summary)
@kindex M-# (Summary)
Remove the process mark, if any, from the current article
(@code{gnus-summary-unmark-as-processable}).

@item M P U
@kindex M P U (Summary)
@findex gnus-summary-unmark-all-processable
Remove the process mark from all articles
(@code{gnus-summary-unmark-all-processable}).

@item M P i
@kindex M P i (Summary)
@findex gnus-uu-invert-processable
Invert the list of process marked articles
(@code{gnus-uu-invert-processable}).

@item M P R
@kindex M P R (Summary)
@findex gnus-uu-mark-by-regexp
Mark articles that have a @code{Subject} header that matches a regular
expression (@code{gnus-uu-mark-by-regexp}).

@item M P G
@kindex M P G (Summary)
@findex gnus-uu-unmark-by-regexp
Unmark articles that have a @code{Subject} header that matches a regular
expression (@code{gnus-uu-unmark-by-regexp}).

@item M P r
@kindex M P r (Summary)
@findex gnus-uu-mark-region
Mark articles in region (@code{gnus-uu-mark-region}).

@item M P g
@kindex M P g (Summary)
@findex gnus-uu-unmark-region
Unmark articles in region (@code{gnus-uu-unmark-region}).

@item M P t
@kindex M P t (Summary)
@findex gnus-uu-mark-thread
Mark all articles in the current (sub)thread
(@code{gnus-uu-mark-thread}).

@item M P T
@kindex M P T (Summary)
@findex gnus-uu-unmark-thread
Unmark all articles in the current (sub)thread
(@code{gnus-uu-unmark-thread}).

@item M P v
@kindex M P v (Summary)
@findex gnus-uu-mark-over
Mark all articles that have a score above the prefix argument
(@code{gnus-uu-mark-over}).

@item M P s
@kindex M P s (Summary)
@findex gnus-uu-mark-series
Mark all articles in the current series (@code{gnus-uu-mark-series}).

@item M P S
@kindex M P S (Summary)
@findex gnus-uu-mark-sparse
Mark all series that have already had some articles marked
(@code{gnus-uu-mark-sparse}).

@item M P a
@kindex M P a (Summary)
@findex gnus-uu-mark-all
Mark all articles in series order (@code{gnus-uu-mark-all}).

@item M P b
@kindex M P b (Summary)
@findex gnus-uu-mark-buffer
Mark all articles in the buffer in the order they appear
(@code{gnus-uu-mark-buffer}).

@item M P k
@kindex M P k (Summary)
@findex gnus-summary-kill-process-mark
Push the current process mark set onto the stack and unmark all articles
(@code{gnus-summary-kill-process-mark}).

@item M P y
@kindex M P y (Summary)
@findex gnus-summary-yank-process-mark
Pop the previous process mark set from the stack and restore it
(@code{gnus-summary-yank-process-mark}).

@item M P w
@kindex M P w (Summary)
@findex gnus-summary-save-process-mark
Push the current process mark set onto the stack
(@code{gnus-summary-save-process-mark}).

@end table

Also see the @kbd{&} command in @ref{Searching for Articles}, for how to
set process marks based on article body contents.


@node Limiting
@section Limiting
@cindex limiting

It can be convenient to limit the summary buffer to just show some
subset of the articles currently in the group.  The effect most limit
commands have is to remove a few (or many) articles from the summary
buffer.

Limiting commands work on subsets of the articles already fetched from
the servers.  These commands don't query the server for additional
articles.

@table @kbd

@item / /
@itemx / s
@kindex / / (Summary)
@findex gnus-summary-limit-to-subject
Limit the summary buffer to articles that match some subject
(@code{gnus-summary-limit-to-subject}).  If given a prefix, exclude
matching articles.

@item / a
@kindex / a (Summary)
@findex gnus-summary-limit-to-author
Limit the summary buffer to articles that match some author
(@code{gnus-summary-limit-to-author}).  If given a prefix, exclude
matching articles.

@item / R
@kindex / R (Summary)
@findex gnus-summary-limit-to-recipient
Limit the summary buffer to articles that match some recipient
(@code{gnus-summary-limit-to-recipient}).  If given a prefix, exclude
matching articles.

@item / A
@kindex / A (Summary)
@findex gnus-summary-limit-to-address
Limit the summary buffer to articles in which contents of From, To or Cc
header match a given address (@code{gnus-summary-limit-to-address}).  If
given a prefix, exclude matching articles.

@item / S
@kindex / S (Summary)
@findex gnus-summary-limit-to-singletons
Limit the summary buffer to articles that aren't part of any displayed
threads (@code{gnus-summary-limit-to-singletons}).  If given a prefix,
limit to articles that are part of displayed threads.

@item / x
@kindex / x (Summary)
@findex gnus-summary-limit-to-extra
Limit the summary buffer to articles that match one of the ``extra''
headers (@pxref{To From Newsgroups})
(@code{gnus-summary-limit-to-extra}).  If given a prefix, exclude
matching articles.

@item / u
@itemx x
@kindex / u (Summary)
@kindex x (Summary)
@findex gnus-summary-limit-to-unread
Limit the summary buffer to articles not marked as read
(@code{gnus-summary-limit-to-unread}).  If given a prefix, limit the
buffer to articles strictly unread.  This means that ticked and
dormant articles will also be excluded.

@item / m
@kindex / m (Summary)
@findex gnus-summary-limit-to-marks
Ask for a mark and then limit to all articles that have been marked
with that mark (@code{gnus-summary-limit-to-marks}).

@item / t
@kindex / t (Summary)
@findex gnus-summary-limit-to-age
Ask for a number and then limit the summary buffer to articles older than (or equal to) that number of days
(@code{gnus-summary-limit-to-age}).  If given a prefix, limit to
articles younger than that number of days.

@item / n
@kindex / n (Summary)
@findex gnus-summary-limit-to-articles
With prefix @samp{n}, limit the summary buffer to the next @samp{n}
articles.  If not given a prefix, use the process marked articles
instead.  (@code{gnus-summary-limit-to-articles}).

@item / w
@kindex / w (Summary)
@findex gnus-summary-pop-limit
Pop the previous limit off the stack and restore it
(@code{gnus-summary-pop-limit}).  If given a prefix, pop all limits off
the stack.

@item / .
@kindex / . (Summary)
@findex gnus-summary-limit-to-unseen
Limit the summary buffer to the unseen articles
(@code{gnus-summary-limit-to-unseen}).

@item / v
@kindex / v (Summary)
@findex gnus-summary-limit-to-score
Limit the summary buffer to articles that have a score at or above some
score (@code{gnus-summary-limit-to-score}).

@item / p
@kindex / p (Summary)
@findex gnus-summary-limit-to-display-predicate
Limit the summary buffer to articles that satisfy the @code{display}
group parameter predicate
(@code{gnus-summary-limit-to-display-predicate}).  @xref{Group
Parameters}, for more on this predicate.

@item / r
@kindex / r (Summary)
@findex gnus-summary-limit-to-replied
Limit the summary buffer to replied articles
(@code{gnus-summary-limit-to-replied}).  If given a prefix, exclude
replied articles.

@item / E
@itemx M S
@kindex M S (Summary)
@kindex / E (Summary)
@findex gnus-summary-limit-include-expunged
Include all expunged articles in the limit
(@code{gnus-summary-limit-include-expunged}).

@item / D
@kindex / D (Summary)
@findex gnus-summary-limit-include-dormant
Include all dormant articles in the limit
(@code{gnus-summary-limit-include-dormant}).

@item / *
@kindex / * (Summary)
@findex gnus-summary-limit-include-cached
Include all cached articles in the limit
(@code{gnus-summary-limit-include-cached}).

@item / d
@kindex / d (Summary)
@findex gnus-summary-limit-exclude-dormant
Exclude all dormant articles from the limit
(@code{gnus-summary-limit-exclude-dormant}).

@item / M
@kindex / M (Summary)
@findex gnus-summary-limit-exclude-marks
Exclude all marked articles (@code{gnus-summary-limit-exclude-marks}).

@item / T
@kindex / T (Summary)
@findex gnus-summary-limit-include-thread
Include all the articles in the current thread in the limit.

@item / c
@kindex / c (Summary)
@findex gnus-summary-limit-exclude-childless-dormant
Exclude all dormant articles that have no children from the limit@*
(@code{gnus-summary-limit-exclude-childless-dormant}).

@item / C
@kindex / C (Summary)
@findex gnus-summary-limit-mark-excluded-as-read
Mark all excluded unread articles as read
(@code{gnus-summary-limit-mark-excluded-as-read}).  If given a prefix,
also mark excluded ticked and dormant articles as read.

@item / b
@kindex / b (Summary)
@findex gnus-summary-limit-to-bodies
Limit the summary buffer to articles that have bodies that match a
certain regexp (@code{gnus-summary-limit-to-bodies}).  If given a
prefix, reverse the limit.  This command is quite slow since it
requires selecting each article to find the matches.

@item / h
@kindex / h (Summary)
@findex gnus-summary-limit-to-headers
Like the previous command, only limit to headers instead
(@code{gnus-summary-limit-to-headers}).

@end table


The following commands aren't limiting commands, but use the @kbd{/}
prefix as well.

@table @kbd
@item / N
@kindex / N (Summary)
@findex gnus-summary-insert-new-articles
Insert all new articles in the summary buffer.  It scans for new emails
if @var{back-end}@code{-get-new-mail} is non-@code{nil}.

@item / o
@kindex / o (Summary)
@findex gnus-summary-insert-old-articles
Insert all old articles in the summary buffer.  If given a numbered
prefix, fetch this number of articles.

@end table


@node Threading
@section Threading
@cindex threading
@cindex article threading

Gnus threads articles by default.  @dfn{To thread} is to put responses
to articles directly after the articles they respond to---in a
hierarchical fashion.

Threading is done by looking at the @code{References} headers of the
articles.  In a perfect world, this would be enough to build pretty
trees, but unfortunately, the @code{References} header is often broken
or simply missing.  Weird news propagation exacerbates the problem,
so one has to employ other heuristics to get pleasing results.  A
plethora of approaches exists, as detailed in horrible detail in
@ref{Customizing Threading}.

First, a quick overview of the concepts:

@table @dfn
@item root
The top-most article in a thread; the first article in the thread.

@item thread
A tree-like article structure.

@item sub-thread
A small(er) section of this tree-like structure.

@item loose threads
Threads often lose their roots due to article expiry, or due to the root
already having been read in a previous session, and not displayed in the
summary buffer.  We then typically have many sub-threads that really
belong to one thread, but are without connecting roots.  These are
called loose threads.

@item thread gathering
An attempt to gather loose threads into bigger threads.

@item sparse threads
A thread where the missing articles have been ``guessed'' at, and are
displayed as empty lines in the summary buffer.

@end table


@menu
* Customizing Threading::       Variables you can change to affect the threading.
* Thread Commands::             Thread based commands in the summary buffer.
@end menu


@node Customizing Threading
@subsection Customizing Threading
@cindex customizing threading

@menu
* Loose Threads::               How Gnus gathers loose threads into bigger threads.
* Filling In Threads::          Making the threads displayed look fuller.
* More Threading::              Even more variables for fiddling with threads.
* Low-Level Threading::         You thought it was over@dots{} but you were wrong!
@end menu


@node Loose Threads
@subsubsection Loose Threads
@cindex <
@cindex >
@cindex loose threads

@table @code
@item gnus-summary-make-false-root
@vindex gnus-summary-make-false-root
If non-@code{nil}, Gnus will gather all loose subtrees into one big tree
and create a dummy root at the top.  (Wait a minute.  Root at the top?
Yup.)  Loose subtrees occur when the real root has expired, or you've
read or killed the root in a previous session.

When there is no real root of a thread, Gnus will have to fudge
something.  This variable says what fudging method Gnus should use.
There are four possible values:

@iftex
@iflatex
\gnusfigure{The Summary Buffer}{390}{
\put(0,0){\epsfig{figure=ps/summary-adopt,width=7.5cm}}
\put(445,0){\makebox(0,0)[br]{\epsfig{figure=ps/summary-empty,width=7.5cm}}}
\put(0,400){\makebox(0,0)[tl]{\epsfig{figure=ps/summary-none,width=7.5cm}}}
\put(445,400){\makebox(0,0)[tr]{\epsfig{figure=ps/summary-dummy,width=7.5cm}}}
}
@end iflatex
@end iftex

@cindex adopting articles

@table @code

@item adopt
Gnus will make the first of the orphaned articles the parent.  This
parent will adopt all the other articles.  The adopted articles will be
marked as such by pointy brackets (@samp{<>}) instead of the standard
square brackets (@samp{[]}).  This is the default method.

@item dummy
@vindex gnus-summary-dummy-line-format
@vindex gnus-summary-make-false-root-always
Gnus will create a dummy summary line that will pretend to be the
parent.  This dummy line does not correspond to any real article, so
selecting it will just select the first real article after the dummy
article.  @code{gnus-summary-dummy-line-format} is used to specify the
format of the dummy roots.  It accepts only one format spec:  @samp{S},
which is the subject of the article.  @xref{Formatting Variables}.
If you want all threads to have a dummy root, even the non-gathered
ones, set @code{gnus-summary-make-false-root-always} to @code{t}.

@item empty
Gnus won't actually make any article the parent, but simply leave the
subject field of all orphans except the first empty.  (Actually, it will
use @code{gnus-summary-same-subject} as the subject (@pxref{Summary
Buffer Format}).)

@item none
Don't make any article parent at all.  Just gather the threads and
display them after one another.

@item nil
Don't gather loose threads.
@end table

@item gnus-summary-gather-subject-limit
@vindex gnus-summary-gather-subject-limit
Loose threads are gathered by comparing subjects of articles.  If this
variable is @code{nil}, Gnus requires an exact match between the
subjects of the loose threads before gathering them into one big
super-thread.  This might be too strict a requirement, what with the
presence of stupid newsreaders that chop off long subject lines.  If
you think so, set this variable to, say, 20 to require that only the
first 20 characters of the subjects have to match.  If you set this
variable to a really low number, you'll find that Gnus will gather
everything in sight into one thread, which isn't very helpful.

@cindex fuzzy article gathering
If you set this variable to the special value @code{fuzzy}, Gnus will
use a fuzzy string comparison algorithm on the subjects (@pxref{Fuzzy
Matching}).

@item gnus-simplify-subject-fuzzy-regexp
@vindex gnus-simplify-subject-fuzzy-regexp
This can either be a regular expression or list of regular expressions
that match strings that will be removed from subjects if fuzzy subject
simplification is used.

@item gnus-simplify-ignored-prefixes
@vindex gnus-simplify-ignored-prefixes
If you set @code{gnus-summary-gather-subject-limit} to something as low
as 10, you might consider setting this variable to something sensible:

@c Written by Michael Ernst <mernst@cs.rice.edu>
@lisp
(setq gnus-simplify-ignored-prefixes
      (concat
       "\\`\\[?\\("
       (mapconcat
        'identity
        '("looking"
          "wanted" "followup" "summary\\( of\\)?"
          "help" "query" "problem" "question"
          "answer" "reference" "announce"
          "How can I" "How to" "Comparison of"
          ;; ...
          )
        "\\|")
       "\\)\\s *\\("
       (mapconcat 'identity
                  '("for" "for reference" "with" "about")
                  "\\|")
       "\\)?\\]?:?[ \t]*"))
@end lisp

All words that match this regexp will be removed before comparing two
subjects.

@item gnus-simplify-subject-functions
@vindex gnus-simplify-subject-functions
If non-@code{nil}, this variable overrides
@code{gnus-summary-gather-subject-limit}.  This variable should be a
list of functions to apply to the @code{Subject} string iteratively to
arrive at the simplified version of the string.

Useful functions to put in this list include:

@table @code
@item gnus-simplify-subject-re
@findex gnus-simplify-subject-re
Strip the leading @samp{Re:}.

@item gnus-simplify-subject-fuzzy
@findex gnus-simplify-subject-fuzzy
Simplify fuzzily.

@item gnus-simplify-whitespace
@findex gnus-simplify-whitespace
Remove excessive whitespace.

@item gnus-simplify-all-whitespace
@findex gnus-simplify-all-whitespace
Remove all whitespace.
@end table

You may also write your own functions, of course.


@item gnus-summary-gather-exclude-subject
@vindex gnus-summary-gather-exclude-subject
Since loose thread gathering is done on subjects only, that might lead
to many false hits, especially with certain common subjects like
@samp{} and @samp{(none)}.  To make the situation slightly better,
you can use the regexp @code{gnus-summary-gather-exclude-subject} to say
what subjects should be excluded from the gathering process.@*
The default is @samp{^ *$\\|^(none)$}.

@item gnus-summary-thread-gathering-function
@vindex gnus-summary-thread-gathering-function
Gnus gathers threads by looking at @code{Subject} headers.  This means
that totally unrelated articles may end up in the same ``thread'', which
is confusing.  An alternate approach is to look at all the
@code{Message-ID}s in all the @code{References} headers to find matches.
This will ensure that no gathered threads ever include unrelated
articles, but it also means that people who have posted with broken
newsreaders won't be gathered properly.  The choice is yours---plague or
cholera:

@table @code
@item gnus-gather-threads-by-subject
@findex gnus-gather-threads-by-subject
This function is the default gathering function and looks at
@code{Subject}s exclusively.

@item gnus-gather-threads-by-references
@findex gnus-gather-threads-by-references
This function looks at @code{References} headers exclusively.
@end table

If you want to test gathering by @code{References}, you could say
something like:

@lisp
(setq gnus-summary-thread-gathering-function
      'gnus-gather-threads-by-references)
@end lisp

@end table


@node Filling In Threads
@subsubsection Filling In Threads

@table @code
@item gnus-fetch-old-headers
@vindex gnus-fetch-old-headers
If non-@code{nil}, Gnus will attempt to build old threads by fetching
more old headers---headers to articles marked as read.  If you would
like to display as few summary lines as possible, but still connect as
many loose threads as possible, you should set this variable to
@code{some} or a number.  If you set it to a number, no more than that
number of extra old headers will be fetched.  In either case, fetching
old headers only works if the back end you are using carries overview
files---this would normally be @code{nntp}, @code{nnspool},
@code{nnml}, and @code{nnmaildir}.  Also remember that if the root of
the thread has been expired by the server, there's not much Gnus can
do about that.

This variable can also be set to @code{invisible}.  This won't have any
visible effects, but is useful if you use the @kbd{A T} command a lot
(@pxref{Finding the Parent}).

The server has to support @acronym{NOV} for any of this to work.

@cindex Gmane, gnus-fetch-old-headers
This feature can seriously impact performance it ignores all locally
cached header entries.  Setting it to @code{t} for groups for a server
that doesn't expire articles (such as news.gmane.org), leads to very
slow summary generation.

@item gnus-fetch-old-ephemeral-headers
@vindex gnus-fetch-old-ephemeral-headers
Same as @code{gnus-fetch-old-headers}, but only used for ephemeral
newsgroups.

@item gnus-build-sparse-threads
@vindex gnus-build-sparse-threads
Fetching old headers can be slow.  A low-rent similar effect can be
gotten by setting this variable to @code{some}.  Gnus will then look at
the complete @code{References} headers of all articles and try to string
together articles that belong in the same thread.  This will leave
@dfn{gaps} in the threading display where Gnus guesses that an article
is missing from the thread.  (These gaps appear like normal summary
lines.  If you select a gap, Gnus will try to fetch the article in
question.)  If this variable is @code{t}, Gnus will display all these
``gaps'' without regard for whether they are useful for completing the
thread or not.  Finally, if this variable is @code{more}, Gnus won't cut
off sparse leaf nodes that don't lead anywhere.  This variable is
@code{nil} by default.

@item gnus-read-all-available-headers
@vindex gnus-read-all-available-headers
This is a rather obscure variable that few will find useful.  It's
intended for those non-news newsgroups where the back end has to fetch
quite a lot to present the summary buffer, and where it's impossible to
go back to parents of articles.  This is mostly the case in the
web-based groups.

If you don't use those, then it's safe to leave this as the default
@code{nil}.  If you want to use this variable, it should be a regexp
that matches the group name, or @code{t} for all groups.

@end table


@node More Threading
@subsubsection More Threading

@table @code
@item gnus-show-threads
@vindex gnus-show-threads
If this variable is @code{nil}, no threading will be done, and all of
the rest of the variables here will have no effect.  Turning threading
off will speed group selection up a bit, but it is sure to make reading
slower and more awkward.

@item gnus-thread-hide-subtree
@vindex gnus-thread-hide-subtree
If non-@code{nil}, all threads will be hidden when the summary buffer is
generated.

This can also be a predicate specifier (@pxref{Predicate Specifiers}).
Available predicates are @code{gnus-article-unread-p} and
@code{gnus-article-unseen-p}.

Here's an example:

@lisp
(setq gnus-thread-hide-subtree
      '(or gnus-article-unread-p
           gnus-article-unseen-p))
@end lisp

(It's a pretty nonsensical example, since all unseen articles are also
unread, but you get my drift.)


@item gnus-thread-expunge-below
@vindex gnus-thread-expunge-below
All threads that have a total score (as defined by
@code{gnus-thread-score-function}) less than this number will be
expunged.  This variable is @code{nil} by default, which means that no
threads are expunged.

@item gnus-thread-hide-killed
@vindex gnus-thread-hide-killed
if you kill a thread and this variable is non-@code{nil}, the subtree
will be hidden.

@item gnus-thread-ignore-subject
@vindex gnus-thread-ignore-subject
Sometimes somebody changes the subject in the middle of a thread.  If
this variable is non-@code{nil}, which is the default, the subject
change is ignored.  If it is @code{nil}, a change in the subject will
result in a new thread.

@item gnus-thread-indent-level
@vindex gnus-thread-indent-level
This is a number that says how much each sub-thread should be indented.
The default is 4.

@item gnus-sort-gathered-threads-function
@vindex gnus-sort-gathered-threads-function
Sometimes, particularly with mailing lists, the order in which mails
arrive locally is not necessarily the same as the order in which they
arrived on the mailing list.  Consequently, when sorting sub-threads
using the default @code{gnus-thread-sort-by-number}, responses can end
up appearing before the article to which they are responding to.
Setting this variable to an alternate value
(e.g., @code{gnus-thread-sort-by-date}), in a group's parameters or in an
appropriate hook (e.g., @code{gnus-summary-generate-hook}) can produce a
more logical sub-thread ordering in such instances.

@end table


@node Low-Level Threading
@subsubsection Low-Level Threading

@table @code

@item gnus-parse-headers-hook
@vindex gnus-parse-headers-hook
Hook run before parsing any headers.

@item gnus-alter-header-function
@vindex gnus-alter-header-function
If non-@code{nil}, this function will be called to allow alteration of
article header structures.  The function is called with one parameter,
the article header vector, which it may alter in any way.  For instance,
if you have a mail-to-news gateway which alters the @code{Message-ID}s
in systematic ways (by adding prefixes and such), you can use this
variable to un-scramble the @code{Message-ID}s so that they are more
meaningful.  Here's one example:

@lisp
(setq gnus-alter-header-function 'my-alter-message-id)

(defun my-alter-message-id (header)
  (let ((id (mail-header-id header)))
    (when (string-match
           "\\(<[^<>@@]*\\)\\.?cygnus\\..*@@\\([^<>@@]*>\\)" id)
      (mail-header-set-id
       (concat (match-string 1 id) "@@" (match-string 2 id))
       header))))
@end lisp

@end table


@node Thread Commands
@subsection Thread Commands
@cindex thread commands

@table @kbd

@item T k
@itemx C-M-k
@kindex T k (Summary)
@kindex C-M-k (Summary)
@findex gnus-summary-kill-thread
Mark all articles in the current (sub-)thread as read
(@code{gnus-summary-kill-thread}).  If the prefix argument is positive,
remove all marks instead.  If the prefix argument is negative, tick
articles instead.

@item T l
@itemx C-M-l
@kindex T l (Summary)
@kindex C-M-l (Summary)
@findex gnus-summary-lower-thread
Lower the score of the current (sub-)thread
(@code{gnus-summary-lower-thread}).

@item T i
@kindex T i (Summary)
@findex gnus-summary-raise-thread
Increase the score of the current (sub-)thread
(@code{gnus-summary-raise-thread}).

@item T #
@kindex T # (Summary)
@findex gnus-uu-mark-thread
Set the process mark on the current (sub-)thread
(@code{gnus-uu-mark-thread}).

@item T M-#
@kindex T M-# (Summary)
@findex gnus-uu-unmark-thread
Remove the process mark from the current (sub-)thread
(@code{gnus-uu-unmark-thread}).

@item T T
@kindex T T (Summary)
@findex gnus-summary-toggle-threads
Toggle threading (@code{gnus-summary-toggle-threads}).

@item T s
@kindex T s (Summary)
@findex gnus-summary-show-thread
Expose the (sub-)thread hidden under the current article, if any@*
(@code{gnus-summary-show-thread}).

@item T h
@kindex T h (Summary)
@findex gnus-summary-hide-thread
Hide the current (sub-)thread (@code{gnus-summary-hide-thread}).

@item T S
@kindex T S (Summary)
@findex gnus-summary-show-all-threads
Expose all hidden threads (@code{gnus-summary-show-all-threads}).

@item T H
@kindex T H (Summary)
@findex gnus-summary-hide-all-threads
Hide all threads (@code{gnus-summary-hide-all-threads}).

@item T t
@kindex T t (Summary)
@findex gnus-summary-rethread-current
Re-thread the current article's thread
(@code{gnus-summary-rethread-current}).  This works even when the
summary buffer is otherwise unthreaded.

@item T ^
@kindex T ^ (Summary)
@findex gnus-summary-reparent-thread
Make the current article the child of the marked (or previous) article
(@code{gnus-summary-reparent-thread}).

@item T M-^
@kindex T M-^ (Summary)
@findex gnus-summary-reparent-children
Make the current article the parent of the marked articles
(@code{gnus-summary-reparent-children}).

@end table

The following commands are thread movement commands.  They all
understand the numeric prefix.

@table @kbd

@item T n
@kindex T n (Summary)
@itemx C-M-f
@kindex C-M-n (Summary)
@itemx M-down
@kindex M-down (Summary)
@findex gnus-summary-next-thread
Go to the next thread (@code{gnus-summary-next-thread}).

@item T p
@kindex T p (Summary)
@itemx C-M-b
@kindex C-M-p (Summary)
@itemx M-up
@kindex M-up (Summary)
@findex gnus-summary-prev-thread
Go to the previous thread (@code{gnus-summary-prev-thread}).

@item T d
@kindex T d (Summary)
@findex gnus-summary-down-thread
Descend the thread (@code{gnus-summary-down-thread}).

@item T u
@kindex T u (Summary)
@findex gnus-summary-up-thread
Ascend the thread (@code{gnus-summary-up-thread}).

@item T o
@kindex T o (Summary)
@findex gnus-summary-top-thread
Go to the top of the thread (@code{gnus-summary-top-thread}).
@end table

@vindex gnus-thread-operation-ignore-subject
If you ignore subject while threading, you'll naturally end up with
threads that have several different subjects in them.  If you then issue
a command like @kbd{T k} (@code{gnus-summary-kill-thread}) you might not
wish to kill the entire thread, but just those parts of the thread that
have the same subject as the current article.  If you like this idea,
you can fiddle with @code{gnus-thread-operation-ignore-subject}.  If it
is non-@code{nil} (which it is by default), subjects will be ignored
when doing thread commands.  If this variable is @code{nil}, articles in
the same thread with different subjects will not be included in the
operation in question.  If this variable is @code{fuzzy}, only articles
that have subjects fuzzily equal will be included (@pxref{Fuzzy
Matching}).


@node Sorting the Summary Buffer
@section Sorting the Summary Buffer

@findex gnus-thread-sort-by-total-score
@findex gnus-thread-sort-by-date
@findex gnus-thread-sort-by-score
@findex gnus-thread-sort-by-subject
@findex gnus-thread-sort-by-author
@findex gnus-thread-sort-by-recipient
@findex gnus-thread-sort-by-number
@findex gnus-thread-sort-by-random
@vindex gnus-thread-sort-functions
@findex gnus-thread-sort-by-most-recent-number
@findex gnus-thread-sort-by-most-recent-date
If you are using a threaded summary display, you can sort the threads by
setting @code{gnus-thread-sort-functions}, which can be either a single
function, a list of functions, or a list containing functions and
@code{(not some-function)} elements.

By default, sorting is done on article numbers.  Ready-made sorting
predicate functions include @code{gnus-thread-sort-by-number},
@code{gnus-thread-sort-by-author}, @code{gnus-thread-sort-by-recipient},
@code{gnus-thread-sort-by-subject},
@code{gnus-thread-sort-by-date},
@code{gnus-thread-sort-by-score},
@code{gnus-thread-sort-by-most-recent-number},
@code{gnus-thread-sort-by-most-recent-date},
@code{gnus-thread-sort-by-random} and
@code{gnus-thread-sort-by-total-score}.

Each function takes two threads and returns non-@code{nil} if the first
thread should be sorted before the other.  Note that sorting really is
normally done by looking only at the roots of each thread.  Exceptions
to this rule are @code{gnus-thread-sort-by-most-recent-number} and
@code{gnus-thread-sort-by-most-recent-date}.

If you use more than one function, the primary sort key should be the
last function in the list.  You should probably always include
@code{gnus-thread-sort-by-number} in the list of sorting
functions---preferably first.  This will ensure that threads that are
equal with respect to the other sort criteria will be displayed in
ascending article order.

If you would like to sort by reverse score, then by subject, and finally
by number, you could do something like:

@lisp
(setq gnus-thread-sort-functions
      '(gnus-thread-sort-by-number
        gnus-thread-sort-by-subject
        (not gnus-thread-sort-by-total-score)))
@end lisp

The threads that have highest score will be displayed first in the
summary buffer.  When threads have the same score, they will be sorted
alphabetically.  The threads that have the same score and the same
subject will be sorted by number, which is (normally) the sequence in
which the articles arrived.

If you want to sort by score and then reverse arrival order, you could
say something like:

@lisp
(setq gnus-thread-sort-functions
      '((not gnus-thread-sort-by-number)
        gnus-thread-sort-by-score))
@end lisp

@vindex gnus-thread-score-function
The function in the @code{gnus-thread-score-function} variable (default
@code{+}) is used for calculating the total score of a thread.  Useful
functions might be @code{max}, @code{min}, or squared means, or whatever
tickles your fancy.

@findex gnus-article-sort-functions
@findex gnus-article-sort-by-date
@findex gnus-article-sort-by-most-recent-date
@findex gnus-article-sort-by-score
@findex gnus-article-sort-by-subject
@findex gnus-article-sort-by-author
@findex gnus-article-sort-by-random
@findex gnus-article-sort-by-number
@findex gnus-article-sort-by-most-recent-number
If you are using an unthreaded display for some strange reason or
other, you have to fiddle with the @code{gnus-article-sort-functions}
variable.  It is very similar to the
@code{gnus-thread-sort-functions}, except that it uses slightly
different functions for article comparison.  Available sorting
predicate functions are @code{gnus-article-sort-by-number},
@code{gnus-article-sort-by-author},
@code{gnus-article-sort-by-subject}, @code{gnus-article-sort-by-date},
@code{gnus-article-sort-by-random}, and
@code{gnus-article-sort-by-score}.

If you want to sort an unthreaded summary display by subject, you could
say something like:

@lisp
(setq gnus-article-sort-functions
      '(gnus-article-sort-by-number
        gnus-article-sort-by-subject))
@end lisp

You can define group specific sorting via @code{gnus-parameters},
@xref{Group Parameters}.


@node Asynchronous Fetching
@section Asynchronous Article Fetching
@cindex asynchronous article fetching
@cindex article pre-fetch
@cindex pre-fetch

If you read your news from an @acronym{NNTP} server that's far away, the
network latencies may make reading articles a chore.  You have to wait
for a while after pressing @kbd{n} to go to the next article before the
article appears.  Why can't Gnus just go ahead and fetch the article
while you are reading the previous one?  Why not, indeed.

First, some caveats.  There are some pitfalls to using asynchronous
article fetching, especially the way Gnus does it.

Let's say you are reading article 1, which is short, and article 2 is
quite long, and you are not interested in reading that.  Gnus does not
know this, so it goes ahead and fetches article 2.  You decide to read
article 3, but since Gnus is in the process of fetching article 2, the
connection is blocked.

To avoid these situations, Gnus will open two (count 'em two)
connections to the server.  Some people may think this isn't a very nice
thing to do, but I don't see any real alternatives.  Setting up that
extra connection takes some time, so Gnus startup will be slower.

Gnus will fetch more articles than you will read.  This will mean that
the link between your machine and the @acronym{NNTP} server will become more
loaded than if you didn't use article pre-fetch.  The server itself will
also become more loaded---both with the extra article requests, and the
extra connection.

Ok, so now you know that you shouldn't really use this thing@dots{} unless
you really want to.

@vindex gnus-asynchronous
Here's how:  Set @code{gnus-asynchronous} to @code{t}.  The rest should
happen automatically.

@vindex gnus-use-article-prefetch
You can control how many articles are to be pre-fetched by setting
@code{gnus-use-article-prefetch}.  This is 30 by default, which means
that when you read an article in the group, the back end will pre-fetch
the next 30 articles.  If this variable is @code{t}, the back end will
pre-fetch all the articles it can without bound.  If it is
@code{nil}, no pre-fetching will be done.

@vindex gnus-async-prefetch-article-p
@findex gnus-async-unread-p
There are probably some articles that you don't want to pre-fetch---read
articles, for instance.  The @code{gnus-async-prefetch-article-p}
variable controls whether an article is to be pre-fetched.  This
function should return non-@code{nil} when the article in question is
to be pre-fetched.  The default is @code{gnus-async-unread-p}, which
returns @code{nil} on read articles.  The function is called with an
article data structure as the only parameter.

If, for instance, you wish to pre-fetch only unread articles shorter
than 100 lines, you could say something like:

@lisp
(defun my-async-short-unread-p (data)
  "Return non-nil for short, unread articles."
  (and (gnus-data-unread-p data)
       (< (mail-header-lines (gnus-data-header data))
          100)))

(setq gnus-async-prefetch-article-p 'my-async-short-unread-p)
@end lisp

These functions will be called many, many times, so they should
preferably be short and sweet to avoid slowing down Gnus too much.
It's probably a good idea to byte-compile things like this.

@vindex gnus-async-post-fetch-function
@findex gnus-html-prefetch-images
After an article has been prefetched, this
@code{gnus-async-post-fetch-function} will be called.  The buffer will
be narrowed to the region of the article that was fetched.  A useful
value would be @code{gnus-html-prefetch-images}, which will prefetch
and store images referenced in the article, so that you don't have to
wait for them to be fetched when you read the article.  This is useful
for @acronym{HTML} messages that have external images.

@vindex gnus-prefetched-article-deletion-strategy
Articles have to be removed from the asynch buffer sooner or later.  The
@code{gnus-prefetched-article-deletion-strategy} says when to remove
articles.  This is a list that may contain the following elements:

@table @code
@item read
Remove articles when they are read.

@item exit
Remove articles when exiting the group.
@end table

The default value is @code{(read exit)}.

@c @vindex gnus-use-header-prefetch
@c If @code{gnus-use-header-prefetch} is non-@code{nil}, prefetch articles
@c from the next group.


@node Article Caching
@section Article Caching
@cindex article caching
@cindex caching

If you have an @emph{extremely} slow @acronym{NNTP} connection, you may
consider turning article caching on.  Each article will then be stored
locally under your home directory.  As you may surmise, this could
potentially use @emph{huge} amounts of disk space, as well as eat up all
your inodes so fast it will make your head swim.  In vodka.

Used carefully, though, it could be just an easier way to save articles.

@vindex gnus-use-long-file-name
@vindex gnus-cache-directory
@vindex gnus-use-cache
To turn caching on, set @code{gnus-use-cache} to @code{t}.  By default,
all articles ticked or marked as dormant will then be copied
over to your local cache (@code{gnus-cache-directory}).  Whether this
cache is flat or hierarchical is controlled by the
@code{gnus-use-long-file-name} variable, as usual.

When re-selecting a ticked or dormant article, it will be fetched from the
cache instead of from the server.  As articles in your cache will never
expire, this might serve as a method of saving articles while still
keeping them where they belong.  Just mark all articles you want to save
as dormant, and don't worry.

When an article is marked as read, is it removed from the cache.

@vindex gnus-cache-remove-articles
@vindex gnus-cache-enter-articles
The entering/removal of articles from the cache is controlled by the
@code{gnus-cache-enter-articles} and @code{gnus-cache-remove-articles}
variables.  Both are lists of symbols.  The first is @code{(ticked
dormant)} by default, meaning that ticked and dormant articles will be
put in the cache.  The latter is @code{(read)} by default, meaning that
articles marked as read are removed from the cache.  Possibly
symbols in these two lists are @code{ticked}, @code{dormant},
@code{unread} and @code{read}.

@findex gnus-jog-cache
So where does the massive article-fetching and storing come into the
picture?  The @code{gnus-jog-cache} command will go through all
subscribed newsgroups, request all unread articles, score them, and
store them in the cache.  You should only ever, ever ever ever, use this
command if 1) your connection to the @acronym{NNTP} server is really, really,
really slow and 2) you have a really, really, really huge disk.
Seriously.  One way to cut down on the number of articles downloaded is
to score unwanted articles down and have them marked as read.  They will
not then be downloaded by this command.

@vindex gnus-uncacheable-groups
@vindex gnus-cacheable-groups
It is likely that you do not want caching on all groups.  For instance,
if your @code{nnml} mail is located under your home directory, it makes no
sense to cache it somewhere else under your home directory.  Unless you
feel that it's neat to use twice as much space.

To limit the caching, you could set @code{gnus-cacheable-groups} to a
regexp of groups to cache, @samp{^nntp} for instance, or set the
@code{gnus-uncacheable-groups} regexp to @samp{^nnml}, for instance.
Both variables are @code{nil} by default.  If a group matches both
variables, the group is not cached.

@findex gnus-cache-generate-nov-databases
@findex gnus-cache-generate-active
@vindex gnus-cache-active-file
The cache stores information on what articles it contains in its active
file (@code{gnus-cache-active-file}).  If this file (or any other parts
of the cache) becomes all messed up for some reason or other, Gnus
offers two functions that will try to set things right.  @kbd{M-x
gnus-cache-generate-nov-databases} will (re)build all the @acronym{NOV}
files, and @kbd{gnus-cache-generate-active} will (re)generate the active
file.

@findex gnus-cache-move-cache
@code{gnus-cache-move-cache} will move your whole
@code{gnus-cache-directory} to some other location.  You get asked to
where, isn't that cool?

@node Persistent Articles
@section Persistent Articles
@cindex persistent articles

Closely related to article caching, we have @dfn{persistent articles}.
In fact, it's just a different way of looking at caching, and much more
useful in my opinion.

Say you're reading a newsgroup, and you happen on to some valuable gem
that you want to keep and treasure forever.  You'd normally just save it
(using one of the many saving commands) in some file.  The problem with
that is that it's just, well, yucky.  Ideally you'd prefer just having
the article remain in the group where you found it forever; untouched by
the expiry going on at the news server.

This is what a @dfn{persistent article} is---an article that just won't
be deleted.  It's implemented using the normal cache functions, but
you use two explicit commands for managing persistent articles:

@table @kbd

@item *
@kindex * (Summary)
@findex gnus-cache-enter-article
Make the current article persistent (@code{gnus-cache-enter-article}).

@item M-*
@kindex M-* (Summary)
@findex gnus-cache-remove-article
Remove the current article from the persistent articles
(@code{gnus-cache-remove-article}).  This will normally delete the
article.
@end table

Both these commands understand the process/prefix convention.

To avoid having all ticked articles (and stuff) entered into the cache,
you should set @code{gnus-use-cache} to @code{passive} if you're just
interested in persistent articles:

@lisp
(setq gnus-use-cache 'passive)
@end lisp

@node Sticky Articles
@section Sticky Articles
@cindex sticky articles

When you select an article the current article buffer will be reused
according to the value of the variable
@code{gnus-single-article-buffer}.  If its value is non-@code{nil} (the
default) all articles reuse the same article buffer.  Else each group
has its own article buffer.

This implies that it's not possible to have more than one article buffer
in a group at a time.  But sometimes you might want to display all the
latest emails from your mother, your father, your aunt, your uncle and
your 17 cousins to coordinate the next Christmas party.

That's where sticky articles come in handy.  A sticky article buffer
basically is a normal article buffer, but it won't be reused when you
select another article.  You can make an article sticky with:

@table @kbd
@item A S
@kindex A S (Summary)
@findex gnus-sticky-article
Make the current article sticky.  If a prefix arg is given, ask for a
name for this sticky article buffer.
@end table

To close a sticky article buffer you can use these commands:

@table @kbd
@item q
@kindex q (Article)
@findex bury-buffer
Puts this sticky article buffer at the end of the list of all buffers.

@item k
@kindex k (Article)
@findex gnus-kill-sticky-article-buffer
Kills this sticky article buffer.
@end table

To kill all sticky article buffers you can use:

@defun gnus-kill-sticky-article-buffers ARG
Kill all sticky article buffers.
If a prefix ARG is given, ask for confirmation.
@end defun

@node Article Backlog
@section Article Backlog
@cindex backlog
@cindex article backlog

If you have a slow connection, but the idea of using caching seems
unappealing to you (and it is, really), you can help the situation some
by switching on the @dfn{backlog}.  This is where Gnus will buffer
already read articles so that it doesn't have to re-fetch articles
you've already read.  This only helps if you are in the habit of
re-selecting articles you've recently read, of course.  If you never do
that, turning the backlog on will slow Gnus down a little bit, and
increase memory usage some.

@vindex gnus-keep-backlog
If you set @code{gnus-keep-backlog} to a number @var{n}, Gnus will store
at most @var{n} old articles in a buffer for later re-fetching.  If this
variable is non-@code{nil} and is not a number, Gnus will store
@emph{all} read articles, which means that your Emacs will grow without
bound before exploding and taking your machine down with you.  I put
that in there just to keep y'all on your toes.

The default value is 20.


@node Saving Articles
@section Saving Articles
@cindex saving articles

Gnus can save articles in a number of ways.  Below is the documentation
for saving articles in a fairly straight-forward fashion (i.e., little
processing of the article is done before it is saved).  For a different
approach (uudecoding, unsharing) you should use @code{gnus-uu}
(@pxref{Decoding Articles}).

For the commands listed here, the target is a file.  If you want to
save to a group, see the @kbd{B c} (@code{gnus-summary-copy-article})
command (@pxref{Mail Group Commands}).

@vindex gnus-save-all-headers
If @code{gnus-save-all-headers} is non-@code{nil}, Gnus will not delete
unwanted headers before saving the article.

@vindex gnus-saved-headers
If the preceding variable is @code{nil}, all headers that match the
@code{gnus-saved-headers} regexp will be kept, while the rest will be
deleted before saving.

@table @kbd

@item O o
@itemx o
@kindex O o (Summary)
@kindex o (Summary)
@findex gnus-summary-save-article
@c @icon{gnus-summary-save-article}
Save the current article using the default article saver
(@code{gnus-summary-save-article}).

@item O m
@kindex O m (Summary)
@findex gnus-summary-save-article-mail
Save the current article in a Unix mail box (mbox) file
(@code{gnus-summary-save-article-mail}).

@item O r
@kindex O r (Summary)
@findex gnus-summary-save-article-rmail
Save the current article in Rmail format
(@code{gnus-summary-save-article-rmail}).  This is mbox since Emacs 23,
Babyl in older versions.

@item O f
@kindex O f (Summary)
@findex gnus-summary-save-article-file
@c @icon{gnus-summary-save-article-file}
Save the current article in plain file format
(@code{gnus-summary-save-article-file}).

@item O F
@kindex O F (Summary)
@findex gnus-summary-write-article-file
Write the current article in plain file format, overwriting any previous
file contents (@code{gnus-summary-write-article-file}).

@item O b
@kindex O b (Summary)
@findex gnus-summary-save-article-body-file
Save the current article body in plain file format
(@code{gnus-summary-save-article-body-file}).

@item O h
@kindex O h (Summary)
@findex gnus-summary-save-article-folder
Save the current article in mh folder format
(@code{gnus-summary-save-article-folder}).

@item O v
@kindex O v (Summary)
@findex gnus-summary-save-article-vm
Save the current article in a VM folder
(@code{gnus-summary-save-article-vm}).

@item O p
@itemx |
@kindex O p (Summary)
@kindex | (Summary)
@findex gnus-summary-pipe-output
@vindex gnus-summary-pipe-output-default-command
Save the current article in a pipe.  Uhm, like, what I mean is---Pipe
the current article to a process (@code{gnus-summary-pipe-output}).
If given a symbolic prefix (@pxref{Symbolic Prefixes}), include the
complete headers in the piped output.  The symbolic prefix @code{r} is
special; it lets this command pipe a raw article including all headers.
The @code{gnus-summary-pipe-output-default-command} variable can be set
to a string containing the default command and options (default
@code{nil}).

@item O P
@kindex O P (Summary)
@findex gnus-summary-muttprint
@vindex gnus-summary-muttprint-program
Save the current article into muttprint.  That is, print it using the
external program @uref{http://muttprint.sourceforge.net/,
Muttprint}.  The program name and options to use is controlled by the
variable @code{gnus-summary-muttprint-program}.
(@code{gnus-summary-muttprint}).

@end table

@vindex gnus-prompt-before-saving
All these commands use the process/prefix convention
(@pxref{Process/Prefix}).  If you save bunches of articles using these
functions, you might get tired of being prompted for files to save each
and every article in.  The prompting action is controlled by
the @code{gnus-prompt-before-saving} variable, which is @code{always} by
default, giving you that excessive prompting action you know and
loathe.  If you set this variable to @code{t} instead, you'll be prompted
just once for each series of articles you save.  If you like to really
have Gnus do all your thinking for you, you can even set this variable
to @code{nil}, which means that you will never be prompted for files to
save articles in.  Gnus will simply save all the articles in the default
files.


@vindex gnus-default-article-saver
You can customize the @code{gnus-default-article-saver} variable to make
Gnus do what you want it to.  You can use any of the eight ready-made
functions below, or you can create your own.

@table @code

@item gnus-summary-save-in-rmail
@findex gnus-summary-save-in-rmail
@vindex gnus-rmail-save-name
@findex gnus-plain-save-name
This is the default format, that used by the Rmail package.  Since Emacs
23, Rmail uses standard mbox format.  Before this, it used the
@dfn{Babyl} format.  Accordingly, this command writes mbox format since
Emacs 23, unless appending to an existing Babyl file.  In older versions
of Emacs, it always uses Babyl format.  Uses the function in the
@code{gnus-rmail-save-name} variable to get a file name to save the
article in.  The default is @code{gnus-plain-save-name}.

@item gnus-summary-save-in-mail
@findex gnus-summary-save-in-mail
@vindex gnus-mail-save-name
Save in a Unix mail (mbox) file.  Uses the function in the
@code{gnus-mail-save-name} variable to get a file name to save the
article in.  The default is @code{gnus-plain-save-name}.

@item gnus-summary-save-in-file
@findex gnus-summary-save-in-file
@vindex gnus-file-save-name
@findex gnus-numeric-save-name
Append the article straight to an ordinary file.  Uses the function in
the @code{gnus-file-save-name} variable to get a file name to save the
article in.  The default is @code{gnus-numeric-save-name}.

@item gnus-summary-write-to-file
@findex gnus-summary-write-to-file
Write the article straight to an ordinary file.  The file is
overwritten if it exists.  Uses the function in the
@code{gnus-file-save-name} variable to get a file name to save the
article in.  The default is @code{gnus-numeric-save-name}.

@item gnus-summary-save-body-in-file
@findex gnus-summary-save-body-in-file
Append the article body to an ordinary file.  Uses the function in the
@code{gnus-file-save-name} variable to get a file name to save the
article in.  The default is @code{gnus-numeric-save-name}.

@item gnus-summary-write-body-to-file
@findex gnus-summary-write-body-to-file
Write the article body straight to an ordinary file.  The file is
overwritten if it exists.  Uses the function in the
@code{gnus-file-save-name} variable to get a file name to save the
article in.  The default is @code{gnus-numeric-save-name}.

@item gnus-summary-save-in-folder
@findex gnus-summary-save-in-folder
@findex gnus-folder-save-name
@findex gnus-Folder-save-name
@vindex gnus-folder-save-name
@cindex rcvstore
@cindex MH folders
Save the article to an MH folder using @code{rcvstore} from the MH
library.  Uses the function in the @code{gnus-folder-save-name} variable
to get a file name to save the article in.  The default is
@code{gnus-folder-save-name}, but you can also use
@code{gnus-Folder-save-name}, which creates capitalized names.

@item gnus-summary-save-in-vm
@findex gnus-summary-save-in-vm
Save the article in a VM folder.  You have to have the VM mail
reader to use this setting.

@item gnus-summary-save-in-pipe
@findex gnus-summary-save-in-pipe
Pipe the article to a shell command.  This function takes optional two
arguments COMMAND and RAW@.  Valid values for COMMAND include:

@itemize @bullet
@item a string@*
The executable command name and possibly arguments.
@item @code{nil}@*
You will be prompted for the command in the minibuffer.
@item the symbol @code{default}@*
It will be replaced with the command which the variable
@code{gnus-summary-pipe-output-default-command} holds or the command
last used for saving.
@end itemize

Non-@code{nil} value for RAW overrides @code{:decode} and
@code{:headers} properties (see below) and the raw article including all
headers will be piped.
@end table

The symbol of each function may have the following properties:

@table @code
@item :decode
The value non-@code{nil} means save decoded articles.  This is
meaningful only with @code{gnus-summary-save-in-file},
@code{gnus-summary-save-body-in-file},
@code{gnus-summary-write-to-file},
@code{gnus-summary-write-body-to-file}, and
@code{gnus-summary-save-in-pipe}.

@item :function
The value specifies an alternative function which appends, not
overwrites, articles to a file.  This implies that when saving many
articles at a time, @code{gnus-prompt-before-saving} is bound to
@code{t} and all articles are saved in a single file.  This is
meaningful only with @code{gnus-summary-write-to-file} and
@code{gnus-summary-write-body-to-file}.

@item :headers
The value specifies the symbol of a variable of which the value
specifies headers to be saved.  If it is omitted,
@code{gnus-save-all-headers} and @code{gnus-saved-headers} control what
headers should be saved.
@end table

@vindex gnus-article-save-directory
All of these functions, except for the last one, will save the article
in the @code{gnus-article-save-directory}, which is initialized from the
@env{SAVEDIR} environment variable.  This is @file{~/News/} by
default.

As you can see above, the functions use different functions to find a
suitable name of a file to save the article in.  Below is a list of
available functions that generate names:

@table @code

@item gnus-Numeric-save-name
@findex gnus-Numeric-save-name
File names like @file{~/News/Alt.andrea-dworkin/45}.

@item gnus-numeric-save-name
@findex gnus-numeric-save-name
File names like @file{~/News/alt.andrea-dworkin/45}.

@item gnus-Plain-save-name
@findex gnus-Plain-save-name
File names like @file{~/News/Alt.andrea-dworkin}.

@item gnus-plain-save-name
@findex gnus-plain-save-name
File names like @file{~/News/alt.andrea-dworkin}.

@item gnus-sender-save-name
@findex gnus-sender-save-name
File names like @file{~/News/larsi}.
@end table

@vindex gnus-split-methods
You can have Gnus suggest where to save articles by plonking a regexp into
the @code{gnus-split-methods} alist.  For instance, if you would like to
save articles related to Gnus in the file @file{gnus-stuff}, and articles
related to VM in @file{vm-stuff}, you could set this variable to something
like:

@lisp
(("^Subject:.*gnus\\|^Newsgroups:.*gnus" "gnus-stuff")
 ("^Subject:.*vm\\|^Xref:.*vm" "vm-stuff")
 (my-choosing-function "../other-dir/my-stuff")
 ((equal gnus-newsgroup-name "mail.misc") "mail-stuff"))
@end lisp

We see that this is a list where each element is a list that has two
elements---the @dfn{match} and the @dfn{file}.  The match can either be
a string (in which case it is used as a regexp to match on the article
head); it can be a symbol (which will be called as a function with the
group name as a parameter); or it can be a list (which will be
@code{eval}ed).  If any of these actions have a non-@code{nil} result,
the @dfn{file} will be used as a default prompt.  In addition, the
result of the operation itself will be used if the function or form
called returns a string or a list of strings.

You basically end up with a list of file names that might be used when
saving the current article.  (All ``matches'' will be used.)  You will
then be prompted for what you really want to use as a name, with file
name completion over the results from applying this variable.

This variable is @code{((gnus-article-archive-name))} by default, which
means that Gnus will look at the articles it saves for an
@code{Archive-name} line and use that as a suggestion for the file
name.

Here's an example function to clean up file names somewhat.  If you have
lots of mail groups called things like
@samp{nnml:mail.whatever}, you may want to chop off the beginning of
these group names before creating the file name to save to.  The
following will do just that:

@lisp
(defun my-save-name (group)
  (when (string-match "^nnml:mail." group)
    (substring group (match-end 0))))

(setq gnus-split-methods
      '((gnus-article-archive-name)
        (my-save-name)))
@end lisp


@vindex gnus-use-long-file-name
Finally, you have the @code{gnus-use-long-file-name} variable.  If it is
@code{nil}, all the preceding functions will replace all periods
(@samp{.}) in the group names with slashes (@samp{/})---which means that
the functions will generate hierarchies of directories instead of having
all the files in the top level directory
(@file{~/News/alt/andrea-dworkin} instead of
@file{~/News/alt.andrea-dworkin}.)  This variable is @code{t} by default
on most systems.  However, for historical reasons, this is @code{nil} on
Xenix and usg-unix-v machines by default.

This function also affects kill and score file names.  If this variable
is a list, and the list contains the element @code{not-score}, long file
names will not be used for score files, if it contains the element
@code{not-save}, long file names will not be used for saving, and if it
contains the element @code{not-kill}, long file names will not be used
for kill files.

If you'd like to save articles in a hierarchy that looks something like
a spool, you could

@lisp
(setq gnus-use-long-file-name '(not-save)) ; @r{to get a hierarchy}
(setq gnus-default-article-saver
      'gnus-summary-save-in-file)          ; @r{no encoding}
@end lisp

Then just save with @kbd{o}.  You'd then read this hierarchy with
ephemeral @code{nneething} groups---@kbd{G D} in the group buffer, and
the top level directory as the argument (@file{~/News/}).  Then just walk
around to the groups/directories with @code{nneething}.


@node Decoding Articles
@section Decoding Articles
@cindex decoding articles

Sometime users post articles (or series of articles) that have been
encoded in some way or other.  Gnus can decode them for you.

@menu
* Uuencoded Articles::          Uudecode articles.
* Shell Archives::              Unshar articles.
* PostScript Files::            Split PostScript.
* Other Files::                 Plain save and binhex.
* Decoding Variables::          Variables for a happy decoding.
* Viewing Files::               You want to look at the result of the decoding?
@end menu

@cindex series
@cindex article series
All these functions use the process/prefix convention
(@pxref{Process/Prefix}) for finding out what articles to work on, with
the extension that a ``single article'' means ``a single series''.  Gnus
can find out by itself what articles belong to a series, decode all the
articles and unpack/view/save the resulting file(s).

Gnus guesses what articles are in the series according to the following
simplish rule: The subjects must be (nearly) identical, except for the
last two numbers of the line.  (Spaces are largely ignored, however.)

For example: If you choose a subject called @samp{cat.gif (2/3)}, Gnus
will find all the articles that match the regexp @samp{^cat.gif
([0-9]+/[0-9]+).*$}.

Subjects that are non-standard, like @samp{cat.gif (2/3) Part 6 of a
series}, will not be properly recognized by any of the automatic viewing
commands, and you have to mark the articles manually with @kbd{#}.


@node Uuencoded Articles
@subsection Uuencoded Articles
@cindex uudecode
@cindex uuencoded articles

@table @kbd

@item X u
@kindex X u (Summary)
@findex gnus-uu-decode-uu
@c @icon{gnus-uu-decode-uu}
Uudecodes the current series (@code{gnus-uu-decode-uu}).

@item X U
@kindex X U (Summary)
@findex gnus-uu-decode-uu-and-save
Uudecodes and saves the current series
(@code{gnus-uu-decode-uu-and-save}).

@item X v u
@kindex X v u (Summary)
@findex gnus-uu-decode-uu-view
Uudecodes and views the current series (@code{gnus-uu-decode-uu-view}).

@item X v U
@kindex X v U (Summary)
@findex gnus-uu-decode-uu-and-save-view
Uudecodes, views and saves the current series
(@code{gnus-uu-decode-uu-and-save-view}).

@end table

Remember that these all react to the presence of articles marked with
the process mark.  If, for instance, you'd like to decode and save an
entire newsgroup, you'd typically do @kbd{M P a}
(@code{gnus-uu-mark-all}) and then @kbd{X U}
(@code{gnus-uu-decode-uu-and-save}).

All this is very much different from how @code{gnus-uu} worked with
@sc{gnus 4.1}, where you had explicit keystrokes for everything under
the sun.  This version of @code{gnus-uu} generally assumes that you mark
articles in some way (@pxref{Setting Process Marks}) and then press
@kbd{X u}.

@vindex gnus-uu-notify-files
Note: When trying to decode articles that have names matching
@code{gnus-uu-notify-files}, which is hard-coded to
@samp{[Cc][Ii][Nn][Dd][Yy][0-9]+.\\(gif\\|jpg\\)}, @code{gnus-uu} will
automatically post an article on @samp{comp.unix.wizards} saying that
you have just viewed the file in question.  This feature can't be turned
off.


@node Shell Archives
@subsection Shell Archives
@cindex unshar
@cindex shell archives
@cindex shared articles

Shell archives (``shar files'') used to be a popular way to distribute
sources, but it isn't used all that much today.  In any case, we have
some commands to deal with these:

@table @kbd

@item X s
@kindex X s (Summary)
@findex gnus-uu-decode-unshar
Unshars the current series (@code{gnus-uu-decode-unshar}).

@item X S
@kindex X S (Summary)
@findex gnus-uu-decode-unshar-and-save
Unshars and saves the current series (@code{gnus-uu-decode-unshar-and-save}).

@item X v s
@kindex X v s (Summary)
@findex gnus-uu-decode-unshar-view
Unshars and views the current series (@code{gnus-uu-decode-unshar-view}).

@item X v S
@kindex X v S (Summary)
@findex gnus-uu-decode-unshar-and-save-view
Unshars, views and saves the current series
(@code{gnus-uu-decode-unshar-and-save-view}).
@end table


@node PostScript Files
@subsection PostScript Files
@cindex PostScript

@table @kbd

@item X p
@kindex X p (Summary)
@findex gnus-uu-decode-postscript
Unpack the current PostScript series (@code{gnus-uu-decode-postscript}).

@item X P
@kindex X P (Summary)
@findex gnus-uu-decode-postscript-and-save
Unpack and save the current PostScript series
(@code{gnus-uu-decode-postscript-and-save}).

@item X v p
@kindex X v p (Summary)
@findex gnus-uu-decode-postscript-view
View the current PostScript series
(@code{gnus-uu-decode-postscript-view}).

@item X v P
@kindex X v P (Summary)
@findex gnus-uu-decode-postscript-and-save-view
View and save the current PostScript series
(@code{gnus-uu-decode-postscript-and-save-view}).
@end table


@node Other Files
@subsection Other Files

@table @kbd
@item X o
@kindex X o (Summary)
@findex gnus-uu-decode-save
Save the current series
(@code{gnus-uu-decode-save}).

@item X b
@kindex X b (Summary)
@findex gnus-uu-decode-binhex
Unbinhex the current series (@code{gnus-uu-decode-binhex}).  This
doesn't really work yet.

@item X Y
@kindex X Y (Summary)
@findex gnus-uu-decode-yenc
yEnc-decode the current series and save it (@code{gnus-uu-decode-yenc}).
@end table


@node Decoding Variables
@subsection Decoding Variables

Adjective, not verb.

@menu
* Rule Variables::              Variables that say how a file is to be viewed.
* Other Decode Variables::      Other decode variables.
* Uuencoding and Posting::      Variables for customizing uuencoding.
@end menu


@node Rule Variables
@subsubsection Rule Variables
@cindex rule variables

Gnus uses @dfn{rule variables} to decide how to view a file.  All these
variables are of the form

@lisp
      (list '(regexp1 command2)
            '(regexp2 command2)
            ...)
@end lisp

@table @code

@item gnus-uu-user-view-rules
@vindex gnus-uu-user-view-rules
@cindex sox
This variable is consulted first when viewing files.  If you wish to use,
for instance, @code{sox} to convert an @file{.au} sound file, you could
say something like:
@lisp
(setq gnus-uu-user-view-rules
      (list '("\\\\.au$" "sox %s -t .aiff > /dev/audio")))
@end lisp

@item gnus-uu-user-view-rules-end
@vindex gnus-uu-user-view-rules-end
This variable is consulted if Gnus couldn't make any matches from the
user and default view rules.

@item gnus-uu-user-archive-rules
@vindex gnus-uu-user-archive-rules
This variable can be used to say what commands should be used to unpack
archives.
@end table


@node Other Decode Variables
@subsubsection Other Decode Variables

@table @code
@vindex gnus-uu-grabbed-file-functions

@item gnus-uu-grabbed-file-functions
All functions in this list will be called right after each file has been
successfully decoded---so that you can move or view files right away,
and don't have to wait for all files to be decoded before you can do
anything.  Ready-made functions you can put in this list are:

@table @code

@item gnus-uu-grab-view
@findex gnus-uu-grab-view
View the file.

@item gnus-uu-grab-move
@findex gnus-uu-grab-move
Move the file (if you're using a saving function.)
@end table

@item gnus-uu-be-dangerous
@vindex gnus-uu-be-dangerous
Specifies what to do if unusual situations arise during decoding.  If
@code{nil}, be as conservative as possible.  If @code{t}, ignore things
that didn't work, and overwrite existing files.  Otherwise, ask each
time.

@item gnus-uu-ignore-files-by-name
@vindex gnus-uu-ignore-files-by-name
Files with name matching this regular expression won't be viewed.

@item gnus-uu-ignore-files-by-type
@vindex gnus-uu-ignore-files-by-type
Files with a @acronym{MIME} type matching this variable won't be viewed.
Note that Gnus tries to guess what type the file is based on the name.
@code{gnus-uu} is not a @acronym{MIME} package (yet), so this is slightly
kludgy.

@item gnus-uu-tmp-dir
@vindex gnus-uu-tmp-dir
Where @code{gnus-uu} does its work.

@item gnus-uu-do-not-unpack-archives
@vindex gnus-uu-do-not-unpack-archives
Non-@code{nil} means that @code{gnus-uu} won't peek inside archives
looking for files to display.

@item gnus-uu-view-and-save
@vindex gnus-uu-view-and-save
Non-@code{nil} means that the user will always be asked to save a file
after viewing it.

@item gnus-uu-ignore-default-view-rules
@vindex gnus-uu-ignore-default-view-rules
Non-@code{nil} means that @code{gnus-uu} will ignore the default viewing
rules.

@item gnus-uu-ignore-default-archive-rules
@vindex gnus-uu-ignore-default-archive-rules
Non-@code{nil} means that @code{gnus-uu} will ignore the default archive
unpacking commands.

@item gnus-uu-kill-carriage-return
@vindex gnus-uu-kill-carriage-return
Non-@code{nil} means that @code{gnus-uu} will strip all carriage returns
from articles.

@item gnus-uu-unmark-articles-not-decoded
@vindex gnus-uu-unmark-articles-not-decoded
Non-@code{nil} means that @code{gnus-uu} will mark unsuccessfully
decoded articles as unread.

@item gnus-uu-correct-stripped-uucode
@vindex gnus-uu-correct-stripped-uucode
Non-@code{nil} means that @code{gnus-uu} will @emph{try} to fix
uuencoded files that have had trailing spaces deleted.

@item gnus-uu-pre-uudecode-hook
@vindex gnus-uu-pre-uudecode-hook
Hook run before sending a message to @code{uudecode}.

@item gnus-uu-view-with-metamail
@vindex gnus-uu-view-with-metamail
@cindex metamail
Non-@code{nil} means that @code{gnus-uu} will ignore the viewing
commands defined by the rule variables and just fudge a @acronym{MIME}
content type based on the file name.  The result will be fed to
@code{metamail} for viewing.

@item gnus-uu-save-in-digest
@vindex gnus-uu-save-in-digest
Non-@code{nil} means that @code{gnus-uu}, when asked to save without
decoding, will save in digests.  If this variable is @code{nil},
@code{gnus-uu} will just save everything in a file without any
embellishments.  The digesting almost conforms to RFC 1153---no easy way
to specify any meaningful volume and issue numbers were found, so I
simply dropped them.

@end table


@node Uuencoding and Posting
@subsubsection Uuencoding and Posting

@table @code

@item gnus-uu-post-include-before-composing
@vindex gnus-uu-post-include-before-composing
Non-@code{nil} means that @code{gnus-uu} will ask for a file to encode
before you compose the article.  If this variable is @code{t}, you can
either include an encoded file with @kbd{C-c C-i} or have one included
for you when you post the article.

@item gnus-uu-post-length
@vindex gnus-uu-post-length
Maximum length of an article.  The encoded file will be split into how
many articles it takes to post the entire file.

@item gnus-uu-post-threaded
@vindex gnus-uu-post-threaded
Non-@code{nil} means that @code{gnus-uu} will post the encoded file in a
thread.  This may not be smart, as no other decoder I have seen is able
to follow threads when collecting uuencoded articles.  (Well, I have
seen one package that does that---@code{gnus-uu}, but somehow, I don't
think that counts@dots{}) Default is @code{nil}.

@item gnus-uu-post-separate-description
@vindex gnus-uu-post-separate-description
Non-@code{nil} means that the description will be posted in a separate
article.  The first article will typically be numbered (0/x).  If this
variable is @code{nil}, the description the user enters will be included
at the beginning of the first article, which will be numbered (1/x).
Default is @code{t}.

@end table


@node Viewing Files
@subsection Viewing Files
@cindex viewing files
@cindex pseudo-articles

After decoding, if the file is some sort of archive, Gnus will attempt
to unpack the archive and see if any of the files in the archive can be
viewed.  For instance, if you have a gzipped tar file @file{pics.tar.gz}
containing the files @file{pic1.jpg} and @file{pic2.gif}, Gnus will
uncompress and de-tar the main file, and then view the two pictures.
This unpacking process is recursive, so if the archive contains archives
of archives, it'll all be unpacked.

Finally, Gnus will normally insert a @dfn{pseudo-article} for each
extracted file into the summary buffer.  If you go to these
``articles'', you will be prompted for a command to run (usually Gnus
will make a suggestion), and then the command will be run.

@vindex gnus-view-pseudo-asynchronously
If @code{gnus-view-pseudo-asynchronously} is @code{nil}, Emacs will wait
until the viewing is done before proceeding.

@vindex gnus-view-pseudos
If @code{gnus-view-pseudos} is @code{automatic}, Gnus will not insert
the pseudo-articles into the summary buffer, but view them
immediately.  If this variable is @code{not-confirm}, the user won't even
be asked for a confirmation before viewing is done.

@vindex gnus-view-pseudos-separately
If @code{gnus-view-pseudos-separately} is non-@code{nil}, one
pseudo-article will be created for each file to be viewed.  If
@code{nil}, all files that use the same viewing command will be given as
a list of parameters to that command.

@vindex gnus-insert-pseudo-articles
If @code{gnus-insert-pseudo-articles} is non-@code{nil}, insert
pseudo-articles when decoding.  It is @code{t} by default.

So; there you are, reading your @emph{pseudo-articles} in your
@emph{virtual newsgroup} from the @emph{virtual server}; and you think:
Why isn't anything real anymore? How did we get here?


@node Article Treatment
@section Article Treatment

Reading through this huge manual, you may have quite forgotten that the
object of newsreaders is to actually, like, read what people have
written.  Reading articles.  Unfortunately, people are quite bad at
writing, so there are tons of functions and variables to make reading
these articles easier.

@menu
* Article Highlighting::        You want to make the article look like fruit salad.
* Article Fontisizing::         Making emphasized text look nice.
* Article Hiding::              You also want to make certain info go away.
* Article Washing::             Lots of way-neat functions to make life better.
* Article Header::              Doing various header transformations.
* Article Buttons::             Click on URLs, Message-IDs, addresses and the like.
* Article Button Levels::       Controlling appearance of buttons.
* Article Date::                Grumble, UT!
* Article Display::             Display various stuff:
                                X-Face, Picons, Gravatars, Smileys.
* Article Signature::           What is a signature?
* Article Miscellanea::         Various other stuff.
@end menu


@node Article Highlighting
@subsection Article Highlighting
@cindex highlighting

Not only do you want your article buffer to look like fruit salad, but
you want it to look like technicolor fruit salad.

@table @kbd

@item W H a
@kindex W H a (Summary)
@findex gnus-article-highlight
@findex gnus-article-maybe-highlight
Do much highlighting of the current article
(@code{gnus-article-highlight}).  This function highlights header, cited
text, the signature, and adds buttons to the body and the head.

@item W H h
@kindex W H h (Summary)
@findex gnus-article-highlight-headers
@vindex gnus-header-face-alist
Highlight the headers (@code{gnus-article-highlight-headers}).  The
highlighting will be done according to the @code{gnus-header-face-alist}
variable, which is a list where each element has the form
@code{(@var{regexp} @var{name} @var{content})}.
@var{regexp} is a regular expression for matching the
header, @var{name} is the face used for highlighting the header name
(@pxref{Faces and Fonts}) and @var{content} is the face for highlighting
the header value.  The first match made will be used.  Note that
@var{regexp} shouldn't have @samp{^} prepended---Gnus will add one.

@item W H c
@kindex W H c (Summary)
@findex gnus-article-highlight-citation
Highlight cited text (@code{gnus-article-highlight-citation}).

Some variables to customize the citation highlights:

@table @code
@vindex gnus-cite-parse-max-size

@item gnus-cite-parse-max-size
If the article size in bytes is bigger than this variable (which is
25000 by default), no citation highlighting will be performed.

@item gnus-cite-max-prefix
@vindex gnus-cite-max-prefix
Maximum possible length for a citation prefix (default 20).

@item gnus-cite-face-list
@vindex gnus-cite-face-list
List of faces used for highlighting citations (@pxref{Faces and Fonts}).
When there are citations from multiple articles in the same message,
Gnus will try to give each citation from each article its own face.
This should make it easier to see who wrote what.

@item gnus-supercite-regexp
@vindex gnus-supercite-regexp
Regexp matching normal Supercite attribution lines.

@item gnus-supercite-secondary-regexp
@vindex gnus-supercite-secondary-regexp
Regexp matching mangled Supercite attribution lines.

@item gnus-cite-minimum-match-count
@vindex gnus-cite-minimum-match-count
Minimum number of identical prefixes we have to see before we believe
that it's a citation.

@item gnus-cite-attribution-prefix
@vindex gnus-cite-attribution-prefix
Regexp matching the beginning of an attribution line.

@item gnus-cite-attribution-suffix
@vindex gnus-cite-attribution-suffix
Regexp matching the end of an attribution line.

@item gnus-cite-attribution-face
@vindex gnus-cite-attribution-face
Face used for attribution lines.  It is merged with the face for the
cited text belonging to the attribution.

@item gnus-cite-ignore-quoted-from
@vindex gnus-cite-ignore-quoted-from
If non-@code{nil}, no citation highlighting will be performed on lines
beginning with @samp{>From }.  Those lines may have been quoted by MTAs
in order not to mix up with the envelope From line.  The default value
is @code{t}.

@end table


@item W H s
@kindex W H s (Summary)
@vindex gnus-signature-separator
@vindex gnus-signature-face
@findex gnus-article-highlight-signature
Highlight the signature (@code{gnus-article-highlight-signature}).
Everything after @code{gnus-signature-separator} (@pxref{Article
Signature}) in an article will be considered a signature and will be
highlighted with @code{gnus-signature-face}, which is @code{italic} by
default.

@end table

@xref{Customizing Articles}, for how to highlight articles automatically.


@node Article Fontisizing
@subsection Article Fontisizing
@cindex emphasis
@cindex article emphasis

@findex gnus-article-emphasize
@kindex W e (Summary)
People commonly add emphasis to words in news articles by writing things
like @samp{_this_} or @samp{*this*} or @samp{/this/}.  Gnus can make
this look nicer by running the article through the @kbd{W e}
(@code{gnus-article-emphasize}) command.

@vindex gnus-emphasis-alist
How the emphasis is computed is controlled by the
@code{gnus-emphasis-alist} variable.  This is an alist where the first
element is a regular expression to be matched.  The second is a number
that says what regular expression grouping is used to find the entire
emphasized word.  The third is a number that says what regexp grouping
should be displayed and highlighted.  (The text between these two
groupings will be hidden.)  The fourth is the face used for
highlighting.

@lisp
(setq gnus-emphasis-alist
      '(("_\\(\\w+\\)_" 0 1 gnus-emphasis-underline)
        ("\\*\\(\\w+\\)\\*" 0 1 gnus-emphasis-bold)))
@end lisp

@cindex slash
@cindex asterisk
@cindex underline
@cindex /
@cindex *

@vindex gnus-emphasis-underline
@vindex gnus-emphasis-bold
@vindex gnus-emphasis-italic
@vindex gnus-emphasis-underline-bold
@vindex gnus-emphasis-underline-italic
@vindex gnus-emphasis-bold-italic
@vindex gnus-emphasis-underline-bold-italic
By default, there are seven rules, and they use the following faces:
@code{gnus-emphasis-bold}, @code{gnus-emphasis-italic},
@code{gnus-emphasis-underline}, @code{gnus-emphasis-bold-italic},
@code{gnus-emphasis-underline-italic},
@code{gnus-emphasis-underline-bold}, and
@code{gnus-emphasis-underline-bold-italic}.

If you want to change these faces, you can either use @kbd{M-x
customize}, or you can use @code{copy-face}.  For instance, if you want
to make @code{gnus-emphasis-italic} use a red face instead, you could
say something like:

@lisp
(copy-face 'red 'gnus-emphasis-italic)
@end lisp

@vindex gnus-group-highlight-words-alist

If you want to highlight arbitrary words, you can use the
@code{gnus-group-highlight-words-alist} variable, which uses the same
syntax as @code{gnus-emphasis-alist}.  The @code{highlight-words} group
parameter (@pxref{Group Parameters}) can also be used.

@xref{Customizing Articles}, for how to fontize articles automatically.


@node Article Hiding
@subsection Article Hiding
@cindex article hiding

Or rather, hiding certain things in each article.  There usually is much
too much cruft in most articles.

@table @kbd

@item W W a
@kindex W W a (Summary)
@findex gnus-article-hide
Do quite a lot of hiding on the article buffer
(@kbd{gnus-article-hide}).  In particular, this function will hide
headers, @acronym{PGP}, cited text and the signature.

@item W W h
@kindex W W h (Summary)
@findex gnus-article-hide-headers
Hide headers (@code{gnus-article-hide-headers}).  @xref{Hiding
Headers}.

@item W W b
@kindex W W b (Summary)
@findex gnus-article-hide-boring-headers
Hide headers that aren't particularly interesting
(@code{gnus-article-hide-boring-headers}).  @xref{Hiding Headers}.

@item W W s
@kindex W W s (Summary)
@findex gnus-article-hide-signature
Hide signature (@code{gnus-article-hide-signature}).  @xref{Article
Signature}.

@item W W l
@kindex W W l (Summary)
@findex gnus-article-hide-list-identifiers
@vindex gnus-list-identifiers
Strip list identifiers specified in @code{gnus-list-identifiers}.  These
are strings some mailing list servers add to the beginning of all
@code{Subject} headers---for example, @samp{[zebra 4711]}.  Any leading
@samp{Re: } is skipped before stripping.  @code{gnus-list-identifiers}
may not contain @code{\\(..\\)}.

@table @code

@item gnus-list-identifiers
@vindex gnus-list-identifiers
A regular expression that matches list identifiers to be removed from
subject.  This can also be a list of regular expressions.

@end table

@item W W P
@kindex W W P (Summary)
@findex gnus-article-hide-pem
Hide @acronym{PEM} (privacy enhanced messages) cruft
(@code{gnus-article-hide-pem}).

@item W W B
@kindex W W B (Summary)
@findex gnus-article-strip-banner
@vindex gnus-article-banner-alist
@vindex gnus-article-address-banner-alist
@cindex banner
@cindex OneList
@cindex stripping advertisements
@cindex advertisements
Strip the banner specified by the @code{banner} group parameter
(@code{gnus-article-strip-banner}).  This is mainly used to hide those
annoying banners and/or signatures that some mailing lists and moderated
groups adds to all the messages.  The way to use this function is to add
the @code{banner} group parameter (@pxref{Group Parameters}) to the
group you want banners stripped from.  The parameter either be a string,
which will be interpreted as a regular expression matching text to be
removed, or the symbol @code{signature}, meaning that the (last)
signature should be removed, or other symbol, meaning that the
corresponding regular expression in @code{gnus-article-banner-alist} is
used.

For instance:

@lisp
(setq gnus-article-banner-alist
      ((googleGroups .
       "^\n*--~--~---------\\(.+\n\\)+")))
@end lisp

Regardless of a group, you can hide things like advertisements only when
the sender of an article has a certain mail address specified in
@code{gnus-article-address-banner-alist}.

@table @code

@item gnus-article-address-banner-alist
@vindex gnus-article-address-banner-alist
Alist of mail addresses and banners.  Each element has the form
@code{(@var{address} . @var{banner})}, where @var{address} is a regexp
matching a mail address in the From header, @var{banner} is one of a
symbol @code{signature}, an item in @code{gnus-article-banner-alist},
a regexp and @code{nil}.  If @var{address} matches author's mail
address, it will remove things like advertisements.  For example, if a
sender has the mail address @samp{hail@@yoo-hoo.co.jp} and there is a
banner something like @samp{Do You Yoo-hoo!?} in all articles he
sends, you can use the following element to remove them:

@lisp
("@@yoo-hoo\\.co\\.jp\\'" .
 "\n_+\nDo You Yoo-hoo!\\?\n.*\n.*\n")
@end lisp

@end table

@item W W c
@kindex W W c (Summary)
@findex gnus-article-hide-citation
Hide citation (@code{gnus-article-hide-citation}).  Some variables for
customizing the hiding:

@table @code

@item gnus-cited-opened-text-button-line-format
@itemx gnus-cited-closed-text-button-line-format
@vindex gnus-cited-closed-text-button-line-format
@vindex gnus-cited-opened-text-button-line-format
Gnus adds buttons to show where the cited text has been hidden, and to
allow toggle hiding the text.  The format of the variable is specified
by these format-like variable (@pxref{Formatting Variables}).  These
specs are valid:

@table @samp
@item b
Starting point of the hidden text.
@item e
Ending point of the hidden text.
@item l
Number of characters in the hidden region.
@item n
Number of lines of hidden text.
@end table

@item gnus-cited-lines-visible
@vindex gnus-cited-lines-visible
The number of lines at the beginning of the cited text to leave
shown.  This can also be a cons cell with the number of lines at the top
and bottom of the text, respectively, to remain visible.

@end table

@item W W C-c
@kindex W W C-c (Summary)
@findex gnus-article-hide-citation-maybe

Hide citation (@code{gnus-article-hide-citation-maybe}) depending on the
following two variables:

@table @code
@item gnus-cite-hide-percentage
@vindex gnus-cite-hide-percentage
If the cited text is of a bigger percentage than this variable (default
50), hide the cited text.

@item gnus-cite-hide-absolute
@vindex gnus-cite-hide-absolute
The cited text must have at least this length (default 10) before it
is hidden.
@end table

@item W W C
@kindex W W C (Summary)
@findex gnus-article-hide-citation-in-followups
Hide cited text in articles that aren't roots
(@code{gnus-article-hide-citation-in-followups}).  This isn't very
useful as an interactive command, but might be a handy function to stick
have happen automatically (@pxref{Customizing Articles}).

@end table

All these ``hiding'' commands are toggles, but if you give a negative
prefix to these commands, they will show what they have previously
hidden.  If you give a positive prefix, they will always hide.

Also @pxref{Article Highlighting} for further variables for
citation customization.

@xref{Customizing Articles}, for how to hide article elements
automatically.


@node Article Washing
@subsection Article Washing
@cindex washing
@cindex article washing

We call this ``article washing'' for a really good reason.  Namely, the
@kbd{A} key was taken, so we had to use the @kbd{W} key instead.

@dfn{Washing} is defined by us as ``changing something from something to
something else'', but normally results in something looking better.
Cleaner, perhaps.

@xref{Customizing Articles}, if you want to change how Gnus displays
articles by default.

@table @kbd

@item C-u g
This is not really washing, it's sort of the opposite of washing.  If
you type this, you see the article exactly as it exists on disk or on
the server.

@item g
Force redisplaying of the current article
(@code{gnus-summary-show-article}).  This is also not really washing.
If you type this, you see the article without any previously applied
interactive Washing functions but with all default treatments
(@pxref{Customizing Articles}).

@item W l
@kindex W l (Summary)
@findex gnus-summary-stop-page-breaking
Remove page breaks from the current article
(@code{gnus-summary-stop-page-breaking}).  @xref{Misc Article}, for page
delimiters.

@item W r
@kindex W r (Summary)
@findex gnus-summary-caesar-message
@c @icon{gnus-summary-caesar-message}
Do a Caesar rotate (rot13) on the article buffer
(@code{gnus-summary-caesar-message}).
Unreadable articles that tell you to read them with Caesar rotate or rot13.
(Typically offensive jokes and such.)

It's commonly called ``rot13'' because each letter is rotated 13
positions in the alphabet, e.g., @samp{B} (letter #2) -> @samp{O} (letter
#15).  It is sometimes referred to as ``Caesar rotate'' because Caesar
is rumored to have employed this form of, uh, somewhat weak encryption.

@item W m
@kindex W m (Summary)
@findex gnus-summary-morse-message
Morse decode the article buffer (@code{gnus-summary-morse-message}).

@item W i
@kindex W i (Summary)
@findex gnus-summary-idna-message
Decode IDNA encoded domain names in the current articles.  IDNA
encoded domain names looks like @samp{xn--bar}.  If a string remain
unencoded after running invoking this, it is likely an invalid IDNA
string (@samp{xn--bar} is invalid).  You must have GNU Libidn
(@url{http://www.gnu.org/software/libidn/}) installed for this command
to work.

@item W t
@item t
@kindex W t (Summary)
@kindex t (Summary)
@findex gnus-summary-toggle-header
Toggle whether to display all headers in the article buffer
(@code{gnus-summary-toggle-header}).

@item W v
@kindex W v (Summary)
@findex gnus-summary-verbose-headers
Toggle whether to display all headers in the article buffer permanently
(@code{gnus-summary-verbose-headers}).

@item W o
@kindex W o (Summary)
@findex gnus-article-treat-overstrike
Treat overstrike (@code{gnus-article-treat-overstrike}).

@item W d
@kindex W d (Summary)
@findex gnus-article-treat-dumbquotes
@vindex gnus-article-dumbquotes-map
@cindex Smartquotes
@cindex M****s*** sm*rtq**t*s
@cindex Latin 1
Treat M****s*** sm*rtq**t*s according to
@code{gnus-article-dumbquotes-map}
(@code{gnus-article-treat-dumbquotes}).  Note that this function guesses
whether a character is a sm*rtq**t* or not, so it should only be used
interactively.

Sm*rtq**t*s are M****s***'s unilateral extension to the character map in
an attempt to provide more quoting characters.  If you see something
like @code{\222} or @code{\264} where you're expecting some kind of
apostrophe or quotation mark, then try this wash.

@item W U
@kindex W U (Summary)
@findex gnus-article-treat-non-ascii
@cindex Unicode
@cindex Non-@acronym{ASCII}
Translate many non-@acronym{ASCII} characters into their
@acronym{ASCII} equivalents (@code{gnus-article-treat-non-ascii}).
This is mostly useful if you're on a terminal that has a limited font
and doesn't show accented characters, ``advanced'' punctuation, and the
like.  For instance, @samp{»} is translated into @samp{>>}, and so on.

@item W Y f
@kindex W Y f (Summary)
@findex gnus-article-outlook-deuglify-article
@cindex Outlook Express
Full deuglify of broken Outlook (Express) articles: Treat dumbquotes,
unwrap lines, repair attribution and rearrange citation.
(@code{gnus-article-outlook-deuglify-article}).

@item W Y u
@kindex W Y u (Summary)
@findex gnus-article-outlook-unwrap-lines
@vindex gnus-outlook-deuglify-unwrap-min
@vindex gnus-outlook-deuglify-unwrap-max
Unwrap lines that appear to be wrapped citation lines.  You can control
what lines will be unwrapped by frobbing
@code{gnus-outlook-deuglify-unwrap-min} and
@code{gnus-outlook-deuglify-unwrap-max}, indicating the minimum and
maximum length of an unwrapped citation line.
(@code{gnus-article-outlook-unwrap-lines}).

@item W Y a
@kindex W Y a (Summary)
@findex gnus-article-outlook-repair-attribution
Repair a broken attribution line.@*
(@code{gnus-article-outlook-repair-attribution}).

@item W Y c
@kindex W Y c (Summary)
@findex gnus-article-outlook-rearrange-citation
Repair broken citations by rearranging the text.
(@code{gnus-article-outlook-rearrange-citation}).

@item W w
@kindex W w (Summary)
@findex gnus-article-fill-cited-article
Do word wrap (@code{gnus-article-fill-cited-article}).

You can give the command a numerical prefix to specify the width to use
when filling.

@item W Q
@kindex W Q (Summary)
@findex gnus-article-fill-long-lines
Fill long lines (@code{gnus-article-fill-long-lines}).

@item W C
@kindex W C (Summary)
@findex gnus-article-capitalize-sentences
Capitalize the first word in each sentence
(@code{gnus-article-capitalize-sentences}).

@item W c
@kindex W c (Summary)
@findex gnus-article-remove-cr
Translate CRLF pairs (i.e., @samp{^M}s on the end of the lines) into LF
(this takes care of DOS line endings), and then translate any remaining
CRs into LF (this takes care of Mac line endings)
(@code{gnus-article-remove-cr}).

@item W q
@kindex W q (Summary)
@findex gnus-article-de-quoted-unreadable
Treat quoted-printable (@code{gnus-article-de-quoted-unreadable}).
Quoted-Printable is one common @acronym{MIME} encoding employed when
sending non-@acronym{ASCII} (i.e., 8-bit) articles.  It typically
makes strings like @samp{d@'ej@`a vu} look like @samp{d=E9j=E0 vu},
which doesn't look very readable to me.  Note that this is usually
done automatically by Gnus if the message in question has a
@code{Content-Transfer-Encoding} header that says that this encoding
has been done.  If a prefix is given, a charset will be asked for.

@item W 6
@kindex W 6 (Summary)
@findex gnus-article-de-base64-unreadable
Treat base64 (@code{gnus-article-de-base64-unreadable}).  Base64 is
one common @acronym{MIME} encoding employed when sending
non-@acronym{ASCII} (i.e., 8-bit) articles.  Note that this is
usually done automatically by Gnus if the message in question has a
@code{Content-Transfer-Encoding} header that says that this encoding
has been done.  If a prefix is given, a charset will be asked for.

@item W Z
@kindex W Z (Summary)
@findex gnus-article-decode-HZ
Treat HZ or HZP (@code{gnus-article-decode-HZ}).  HZ (or HZP) is one
common encoding employed when sending Chinese articles.  It typically
makes strings look like @samp{~@{<:Ky2;S@{#,NpJ)l6HK!#~@}}.

@item W A
@kindex W A (Summary)
@findex gnus-article-treat-ansi-sequences
@cindex @acronym{ANSI} control sequences
Translate @acronym{ANSI} SGR control sequences into overlays or
extents (@code{gnus-article-treat-ansi-sequences}).  @acronym{ANSI}
sequences are used in some Chinese hierarchies for highlighting.

@item W u
@kindex W u (Summary)
@findex gnus-article-unsplit-urls
Remove newlines from within URLs.  Some mailers insert newlines into
outgoing email messages to keep lines short.  This reformatting can
split long URLs onto multiple lines.  Repair those URLs by removing
the newlines (@code{gnus-article-unsplit-urls}).

@item W h
@kindex W h (Summary)
@findex gnus-article-wash-html
Treat @acronym{HTML} (@code{gnus-article-wash-html}).  Note that this is
usually done automatically by Gnus if the message in question has a
@code{Content-Type} header that says that the message is @acronym{HTML}.

If a prefix is given, a charset will be asked for.  If it is a number,
the charset defined in @code{gnus-summary-show-article-charset-alist}
(@pxref{Paging the Article}) will be used.

The default is to use the function specified by
@code{mm-text-html-renderer} (@pxref{Display Customization, ,Display
Customization, emacs-mime, The Emacs MIME Manual}) to convert the
@acronym{HTML}.  Pre-defined functions you can use include:

@table @code
@item shr
Use Gnus simple html renderer.

@item gnus-w3m
Use Gnus rendered based on w3m.

@item w3
Use Emacs/W3.

@item w3m
Use @uref{http://emacs-w3m.namazu.org/, emacs-w3m}.

@item w3m-standalone
Use @uref{http://w3m.sourceforge.net/, w3m}.

@item links
Use @uref{http://links.sf.net/, Links}.

@item lynx
Use @uref{http://lynx.isc.org/, Lynx}.

@item html2text
Use html2text---a simple @acronym{HTML} converter included with Gnus.

@end table

@item W b
@kindex W b (Summary)
@findex gnus-article-add-buttons
Add clickable buttons to the article (@code{gnus-article-add-buttons}).
@xref{Article Buttons}.

@item W B
@kindex W B (Summary)
@findex gnus-article-add-buttons-to-head
Add clickable buttons to the article headers
(@code{gnus-article-add-buttons-to-head}).

@item W p
@kindex W p (Summary)
@findex gnus-article-verify-x-pgp-sig
Verify a signed control message
(@code{gnus-article-verify-x-pgp-sig}).  Control messages such as
@code{newgroup} and @code{checkgroups} are usually signed by the
hierarchy maintainer.  You need to add the @acronym{PGP} public key of
the maintainer to your keyring to verify the
message.@footnote{@acronym{PGP} keys for many hierarchies are
available at @uref{ftp://ftp.isc.org/pub/pgpcontrol/README.html}}

@item W s
@kindex W s (Summary)
@findex gnus-summary-force-verify-and-decrypt
Verify a signed (@acronym{PGP}, @acronym{PGP/MIME} or
@acronym{S/MIME}) message
(@code{gnus-summary-force-verify-and-decrypt}). @xref{Security}.

@item W a
@kindex W a (Summary)
@findex gnus-article-strip-headers-in-body
Strip headers like the @code{X-No-Archive} header from the beginning of
article bodies (@code{gnus-article-strip-headers-in-body}).

@item W E l
@kindex W E l (Summary)
@findex gnus-article-strip-leading-blank-lines
Remove all blank lines from the beginning of the article
(@code{gnus-article-strip-leading-blank-lines}).

@item W E m
@kindex W E m (Summary)
@findex gnus-article-strip-multiple-blank-lines
Replace all blank lines with empty lines and then all multiple empty
lines with a single empty line.
(@code{gnus-article-strip-multiple-blank-lines}).

@item W E t
@kindex W E t (Summary)
@findex gnus-article-remove-trailing-blank-lines
Remove all blank lines at the end of the article
(@code{gnus-article-remove-trailing-blank-lines}).

@item W E a
@kindex W E a (Summary)
@findex gnus-article-strip-blank-lines
Do all the three commands above
(@code{gnus-article-strip-blank-lines}).

@item W E A
@kindex W E A (Summary)
@findex gnus-article-strip-all-blank-lines
Remove all blank lines
(@code{gnus-article-strip-all-blank-lines}).

@item W E s
@kindex W E s (Summary)
@findex gnus-article-strip-leading-space
Remove all white space from the beginning of all lines of the article
body (@code{gnus-article-strip-leading-space}).

@item W E e
@kindex W E e (Summary)
@findex gnus-article-strip-trailing-space
Remove all white space from the end of all lines of the article
body (@code{gnus-article-strip-trailing-space}).

@end table

@xref{Customizing Articles}, for how to wash articles automatically.


@node Article Header
@subsection Article Header

These commands perform various transformations of article header.

@table @kbd

@item W G u
@kindex W G u (Summary)
@findex gnus-article-treat-unfold-headers
Unfold folded header lines (@code{gnus-article-treat-unfold-headers}).

@item W G n
@kindex W G n (Summary)
@findex gnus-article-treat-fold-newsgroups
Fold the @code{Newsgroups} and @code{Followup-To} headers
(@code{gnus-article-treat-fold-newsgroups}).

@item W G f
@kindex W G f (Summary)
@findex gnus-article-treat-fold-headers
Fold all the message headers
(@code{gnus-article-treat-fold-headers}).

@item W E w
@kindex W E w (Summary)
@findex gnus-article-remove-leading-whitespace
Remove excessive whitespace from all headers
(@code{gnus-article-remove-leading-whitespace}).

@end table


@node Article Buttons
@subsection Article Buttons
@cindex buttons

People often include references to other stuff in articles, and it would
be nice if Gnus could just fetch whatever it is that people talk about
with the minimum of fuzz when you hit @kbd{RET} or use the middle mouse
button on these references.

@vindex gnus-button-man-handler
Gnus adds @dfn{buttons} to certain standard references by default:
Well-formed URLs, mail addresses, Message-IDs, Info links, man pages and
Emacs or Gnus related references.  This is controlled by two variables,
one that handles article bodies and one that handles article heads:

@table @code

@item gnus-button-alist
@vindex gnus-button-alist
This is an alist where each entry has this form:

@lisp
(@var{regexp} @var{button-par} @var{use-p} @var{function} @var{data-par})
@end lisp

@table @var

@item regexp
All text that match this regular expression (case insensitive) will be
considered an external reference.  Here's a typical regexp that matches
embedded URLs: @samp{<URL:\\([^\n\r>]*\\)>}.  This can also be a
variable containing a regexp, useful variables to use include
@code{gnus-button-url-regexp} and @code{gnus-button-mid-or-mail-regexp}.

@item button-par
Gnus has to know which parts of the matches is to be highlighted.  This
is a number that says what sub-expression of the regexp is to be
highlighted.  If you want it all highlighted, you use 0 here.

@item use-p
This form will be @code{eval}ed, and if the result is non-@code{nil},
this is considered a match.  This is useful if you want extra sifting to
avoid false matches.  Often variables named
@code{gnus-button-@var{*}-level} are used here, @xref{Article Button
Levels}, but any other form may be used too.

@c @code{use-p} is @code{eval}ed only if @code{regexp} matches.

@item function
This function will be called when you click on this button.

@item data-par
As with @var{button-par}, this is a sub-expression number, but this one
says which part of the match is to be sent as data to @var{function}.

@end table

So the full entry for buttonizing URLs is then

@lisp
("<URL:\\([^\n\r>]*\\)>" 0 t gnus-button-url 1)
@end lisp

@item gnus-header-button-alist
@vindex gnus-header-button-alist
This is just like the other alist, except that it is applied to the
article head only, and that each entry has an additional element that is
used to say what headers to apply the buttonize coding to:

@lisp
(@var{header} @var{regexp} @var{button-par} @var{use-p} @var{function} @var{data-par})
@end lisp

@var{header} is a regular expression.
@end table

@subsubsection Related variables and functions

@table @code
@item gnus-button-@var{*}-level
@xref{Article Button Levels}.

@c Stuff related to gnus-button-browse-level

@item gnus-button-url-regexp
@vindex gnus-button-url-regexp
A regular expression that matches embedded URLs.  It is used in the
default values of the variables above.

@c Stuff related to gnus-button-man-level

@item gnus-button-man-handler
@vindex gnus-button-man-handler
The function to use for displaying man pages.  It must take at least one
argument with a string naming the man page.

@c Stuff related to gnus-button-message-level

@item gnus-button-mid-or-mail-regexp
@vindex gnus-button-mid-or-mail-regexp
Regular expression that matches a message ID or a mail address.

@item gnus-button-prefer-mid-or-mail
@vindex gnus-button-prefer-mid-or-mail
This variable determines what to do when the button on a string as
@samp{foo123@@bar.invalid} is pushed.  Strings like this can be either a
message ID or a mail address.  If it is one of the symbols @code{mid} or
@code{mail}, Gnus will always assume that the string is a message ID or
a mail address, respectively.  If this variable is set to the symbol
@code{ask}, always query the user what to do.  If it is a function, this
function will be called with the string as its only argument.  The
function must return @code{mid}, @code{mail}, @code{invalid} or
@code{ask}.  The default value is the function
@code{gnus-button-mid-or-mail-heuristic}.

@item gnus-button-mid-or-mail-heuristic
@findex gnus-button-mid-or-mail-heuristic
Function that guesses whether its argument is a message ID or a mail
address.  Returns @code{mid} if it's a message IDs, @code{mail} if
it's a mail address, @code{ask} if unsure and @code{invalid} if the
string is invalid.

@item gnus-button-mid-or-mail-heuristic-alist
@vindex gnus-button-mid-or-mail-heuristic-alist
An alist of @code{(RATE . REGEXP)} pairs used by the function
@code{gnus-button-mid-or-mail-heuristic}.

@c Misc stuff

@item gnus-article-button-face
@vindex gnus-article-button-face
Face used on buttons.

@item gnus-article-mouse-face
@vindex gnus-article-mouse-face
Face used when the mouse cursor is over a button.

@end table

@xref{Customizing Articles}, for how to buttonize articles automatically.


@node Article Button Levels
@subsection Article button levels
@cindex button levels
The higher the value of the variables @code{gnus-button-@var{*}-level},
the more buttons will appear.  If the level is zero, no corresponding
buttons are displayed.  With the default value (which is 5) you should
already see quite a lot of buttons.  With higher levels, you will see
more buttons, but you may also get more false positives.  To avoid them,
you can set the variables @code{gnus-button-@var{*}-level} local to
specific groups (@pxref{Group Parameters}).  Here's an example for the
variable @code{gnus-parameters}:

@lisp
;; @r{increase @code{gnus-button-*-level} in some groups:}
(setq gnus-parameters
      '(("\\<\\(emacs\\|gnus\\)\\>" (gnus-button-emacs-level 10))
        ("\\<unix\\>"               (gnus-button-man-level 10))
        ("\\<tex\\>"                (gnus-button-tex-level 10))))
@end lisp

@table @code

@item gnus-button-browse-level
@vindex gnus-button-browse-level
Controls the display of references to message IDs, mail addresses and
news URLs.  Related variables and functions include
@code{gnus-button-url-regexp}, @code{browse-url}, and
@code{browse-url-browser-function}.

@item gnus-button-emacs-level
@vindex gnus-button-emacs-level
Controls the display of Emacs or Gnus references.  Related functions are
@code{gnus-button-handle-custom},
@code{gnus-button-handle-describe-function},
@code{gnus-button-handle-describe-variable},
@code{gnus-button-handle-symbol},
@code{gnus-button-handle-describe-key},
@code{gnus-button-handle-apropos},
@code{gnus-button-handle-apropos-command},
@code{gnus-button-handle-apropos-variable},
@code{gnus-button-handle-apropos-documentation}, and
@code{gnus-button-handle-library}.

@item gnus-button-man-level
@vindex gnus-button-man-level
Controls the display of references to (Unix) man pages.
See @code{gnus-button-man-handler}.

@item gnus-button-message-level
@vindex gnus-button-message-level
Controls the display of message IDs, mail addresses and news URLs.
Related variables and functions include
@code{gnus-button-mid-or-mail-regexp},
@code{gnus-button-prefer-mid-or-mail},
@code{gnus-button-mid-or-mail-heuristic}, and
@code{gnus-button-mid-or-mail-heuristic-alist}.

@end table


@node Article Date
@subsection Article Date

The date is most likely generated in some obscure timezone you've never
heard of, so it's quite nice to be able to find out what the time was
when the article was sent.

@table @kbd

@item W T u
@kindex W T u (Summary)
@findex gnus-article-date-ut
Display the date in UT (aka. GMT, aka ZULU)
(@code{gnus-article-date-ut}).

@item W T i
@kindex W T i (Summary)
@findex gnus-article-date-iso8601
@cindex ISO 8601
Display the date in international format, aka. ISO 8601
(@code{gnus-article-date-iso8601}).

@item W T l
@kindex W T l (Summary)
@findex gnus-article-date-local
Display the date in the local timezone (@code{gnus-article-date-local}).

@item W T p
@kindex W T p (Summary)
@findex gnus-article-date-english
Display the date in a format that's easily pronounceable in English
(@code{gnus-article-date-english}).

@item W T s
@kindex W T s (Summary)
@vindex gnus-article-time-format
@findex gnus-article-date-user
@findex format-time-string
Display the date using a user-defined format
(@code{gnus-article-date-user}).  The format is specified by the
@code{gnus-article-time-format} variable, and is a string that's passed
to @code{format-time-string}.  See the documentation of that variable
for a list of possible format specs.

@item W T e
@kindex W T e (Summary)
@findex gnus-article-date-lapsed
@findex gnus-start-date-timer
@findex gnus-stop-date-timer
Say how much time has elapsed between the article was posted and now
(@code{gnus-article-date-lapsed}).  It looks something like:

@example
Date: 6 weeks, 4 days, 1 hour, 3 minutes, 8 seconds ago
@end example

To make this line updated continually, set the
@code{gnus-article-update-date-headers} variable to the frequency in
seconds (the default is @code{nil}).

@item W T o
@kindex W T o (Summary)
@findex gnus-article-date-original
Display the original date (@code{gnus-article-date-original}).  This can
be useful if you normally use some other conversion function and are
worried that it might be doing something totally wrong.  Say, claiming
that the article was posted in 1854.  Although something like that is
@emph{totally} impossible.  Don't you trust me? *titter*

@end table

@xref{Customizing Articles}, for how to display the date in your
preferred format automatically.


@node Article Display
@subsection Article Display
@cindex picons
@cindex x-face
@cindex smileys
@cindex gravatars

These commands add various frivolous display gimmicks to the article
buffer in Emacs versions that support them.

@code{X-Face} headers are small black-and-white images supplied by the
message headers (@pxref{X-Face}).

@code{Face} headers are small colored images supplied by the message
headers (@pxref{Face}).

Smileys are those little @samp{:-)} symbols that people like to litter
their messages with (@pxref{Smileys}).

Picons, on the other hand, reside on your own system, and Gnus will
try to match the headers to what you have (@pxref{Picons}).

Gravatars reside on-line and are fetched from
@uref{http://www.gravatar.com/} (@pxref{Gravatars}).

All these functions are toggles---if the elements already exist,
they'll be removed.

@table @kbd
@item W D x
@kindex W D x (Summary)
@findex gnus-article-display-x-face
Display an @code{X-Face} in the @code{From} header.
(@code{gnus-article-display-x-face}).

@item W D d
@kindex W D d (Summary)
@findex gnus-article-display-face
Display a @code{Face} in the @code{From} header.
(@code{gnus-article-display-face}).

@item W D s
@kindex W D s (Summary)
@findex gnus-treat-smiley
Display smileys (@code{gnus-treat-smiley}).

@item W D f
@kindex W D f (Summary)
@findex gnus-treat-from-picon
Piconify the @code{From} header (@code{gnus-treat-from-picon}).

@item W D m
@kindex W D m (Summary)
@findex gnus-treat-mail-picon
Piconify all mail headers (i.e., @code{Cc}, @code{To})
(@code{gnus-treat-mail-picon}).

@item W D n
@kindex W D n (Summary)
@findex gnus-treat-newsgroups-picon
Piconify all news headers (i.e., @code{Newsgroups} and
@code{Followup-To}) (@code{gnus-treat-newsgroups-picon}).

@item W D g
@kindex W D g (Summary)
@findex gnus-treat-from-gravatar
Gravatarify the @code{From} header (@code{gnus-treat-from-gravatar}).

@item W D h
@kindex W D h (Summary)
@findex gnus-treat-mail-gravatar
Gravatarify all mail headers (i.e., @code{Cc}, @code{To})
(@code{gnus-treat-from-gravatar}).

@item W D D
@kindex W D D (Summary)
@findex gnus-article-remove-images
Remove all images from the article buffer
(@code{gnus-article-remove-images}).

@item W D W
@kindex W D W (Summary)
@findex gnus-html-show-images
If you're reading an @acronym{HTML} article rendered with
@code{gnus-article-html}, then you can insert any blocked images in
the buffer with this command.
(@code{gnus-html-show-images}).

@end table



@node Article Signature
@subsection Article Signature
@cindex signatures
@cindex article signature

@vindex gnus-signature-separator
Each article is divided into two parts---the head and the body.  The
body can be divided into a signature part and a text part.  The variable
that says what is to be considered a signature is
@code{gnus-signature-separator}.  This is normally the standard
@samp{^-- $} as mandated by son-of-RFC 1036.  However, many people use
non-standard signature separators, so this variable can also be a list
of regular expressions to be tested, one by one.  (Searches are done
from the end of the body towards the beginning.)  One likely value is:

@lisp
(setq gnus-signature-separator
      '("^-- $"         ; @r{The standard}
        "^-- *$"        ; @r{A common mangling}
        "^-------*$"    ; @r{Many people just use a looong}
                        ; @r{line of dashes.  Shame!}
        "^ *--------*$" ; @r{Double-shame!}
        "^________*$"   ; @r{Underscores are also popular}
        "^========*$")) ; @r{Pervert!}
@end lisp

The more permissive you are, the more likely it is that you'll get false
positives.

@vindex gnus-signature-limit
@code{gnus-signature-limit} provides a limit to what is considered a
signature when displaying articles.

@enumerate
@item
If it is an integer, no signature may be longer (in characters) than
that integer.
@item
If it is a floating point number, no signature may be longer (in lines)
than that number.
@item
If it is a function, the function will be called without any parameters,
and if it returns @code{nil}, there is no signature in the buffer.
@item
If it is a string, it will be used as a regexp.  If it matches, the text
in question is not a signature.
@end enumerate

This variable can also be a list where the elements may be of the types
listed above.  Here's an example:

@lisp
(setq gnus-signature-limit
      '(200.0 "^---*Forwarded article"))
@end lisp

This means that if there are more than 200 lines after the signature
separator, or the text after the signature separator is matched by
the regular expression @samp{^---*Forwarded article}, then it isn't a
signature after all.


@node Article Miscellanea
@subsection Article Miscellanea

@table @kbd
@item A t
@kindex A t (Summary)
@findex gnus-article-babel
Translate the article from one language to another
(@code{gnus-article-babel}).

@end table


@node MIME Commands
@section MIME Commands
@cindex MIME decoding
@cindex attachments
@cindex viewing attachments

The following commands all understand the numerical prefix.  For
instance, @kbd{3 K v} means ``view the third @acronym{MIME} part''.

@table @kbd
@item b
@itemx K v
@kindex b (Summary)
@kindex K v (Summary)
View the @acronym{MIME} part.

@item K o
@kindex K o (Summary)
Save the @acronym{MIME} part.

@item K O
@kindex K O (Summary)
Prompt for a file name, then save the @acronym{MIME} part and strip it
from the article.  The stripped @acronym{MIME} object will be referred
via the message/external-body @acronym{MIME} type.

@item K r
@kindex K r (Summary)
Replace the @acronym{MIME} part with an external body.

@item K d
@kindex K d (Summary)
Delete the @acronym{MIME} part and add some information about the
removed part.

@item K c
@kindex K c (Summary)
Copy the @acronym{MIME} part.

@item K e
@kindex K e (Summary)
View the @acronym{MIME} part externally.

@item K i
@kindex K i (Summary)
View the @acronym{MIME} part internally.

@item K |
@kindex K | (Summary)
Pipe the @acronym{MIME} part to an external command.
@end table

The rest of these @acronym{MIME} commands do not use the numerical prefix in
the same manner:

@table @kbd
@item K H
@kindex K H (Summary)
@findex gnus-article-browse-html-article
View @samp{text/html} parts of the current article with a WWW browser.
Inline images embedded in a message using the @code{cid} scheme, as they
are generally considered to be safe, will be processed properly.  The
message header is added to the beginning of every @acronym{HTML} part
unless the prefix argument is given.

Warning: Spammers use links to images (using the @code{http} scheme) in
@acronym{HTML} articles to verify whether you have read the message.  As
this command passes the @acronym{HTML} content to the browser without
eliminating these ``web bugs'' you should only use it for mails from
trusted senders.

If you always want to display @acronym{HTML} parts in the browser, set
@code{mm-text-html-renderer} to @code{nil}.

This command creates temporary files to pass @acronym{HTML} contents
including images if any to the browser, and deletes them when exiting
the group (if you want).

@item K b
@kindex K b (Summary)
Make all the @acronym{MIME} parts have buttons in front of them.  This is
mostly useful if you wish to save (or perform other actions) on inlined
parts.

@item K m
@kindex K m (Summary)
@findex gnus-summary-repair-multipart
Some multipart messages are transmitted with missing or faulty headers.
This command will attempt to ``repair'' these messages so that they can
be viewed in a more pleasant manner
(@code{gnus-summary-repair-multipart}).

@item X m
@kindex X m (Summary)
@findex gnus-summary-save-parts
Save all parts matching a @acronym{MIME} type to a directory
(@code{gnus-summary-save-parts}).  Understands the process/prefix
convention (@pxref{Process/Prefix}).

@item M-t
@kindex M-t (Summary)
@findex gnus-summary-toggle-display-buttonized
Toggle the buttonized display of the article buffer
(@code{gnus-summary-toggle-display-buttonized}).

@item W M w
@kindex W M w (Summary)
@findex gnus-article-decode-mime-words
Decode RFC 2047-encoded words in the article headers
(@code{gnus-article-decode-mime-words}).

@item W M c
@kindex W M c (Summary)
@findex gnus-article-decode-charset
Decode encoded article bodies as well as charsets
(@code{gnus-article-decode-charset}).

This command looks in the @code{Content-Type} header to determine the
charset.  If there is no such header in the article, you can give it a
prefix, which will prompt for the charset to decode as.  In regional
groups where people post using some common encoding (but do not
include @acronym{MIME} headers), you can set the @code{charset} group/topic
parameter to the required charset (@pxref{Group Parameters}).

@item W M v
@kindex W M v (Summary)
@findex gnus-mime-view-all-parts
View all the @acronym{MIME} parts in the current article
(@code{gnus-mime-view-all-parts}).

@end table

Relevant variables:

@table @code
@item gnus-ignored-mime-types
@vindex gnus-ignored-mime-types
This is a list of regexps.  @acronym{MIME} types that match a regexp from
this list will be completely ignored by Gnus.  The default value is
@code{nil}.

To have all Vcards be ignored, you'd say something like this:

@lisp
(setq gnus-ignored-mime-types
      '("text/x-vcard"))
@end lisp

@item gnus-article-loose-mime
@vindex gnus-article-loose-mime
If non-@code{nil}, Gnus won't require the @samp{MIME-Version} header
before interpreting the message as a @acronym{MIME} message.  This helps
when reading messages from certain broken mail user agents.  The
default is @code{t}.

@item gnus-article-emulate-mime
@vindex gnus-article-emulate-mime
@cindex uuencode
@cindex yEnc
There are other, non-@acronym{MIME} encoding methods used.  The most common
is @samp{uuencode}, but yEncode is also getting to be popular.  If
this variable is non-@code{nil}, Gnus will look in message bodies to
see if it finds these encodings, and if so, it'll run them through the
Gnus @acronym{MIME} machinery.  The default is @code{t}.  Only
single-part yEnc encoded attachments can be decoded.  There's no support
for encoding in Gnus.

@item gnus-unbuttonized-mime-types
@vindex gnus-unbuttonized-mime-types
This is a list of regexps.  @acronym{MIME} types that match a regexp from
this list won't have @acronym{MIME} buttons inserted unless they aren't
displayed or this variable is overridden by
@code{gnus-buttonized-mime-types}.  The default value is
@code{(".*/.*")}.  This variable is only used when
@code{gnus-inhibit-mime-unbuttonizing} is @code{nil}.

@item gnus-buttonized-mime-types
@vindex gnus-buttonized-mime-types
This is a list of regexps.  @acronym{MIME} types that match a regexp from
this list will have @acronym{MIME} buttons inserted unless they aren't
displayed.  This variable overrides
@code{gnus-unbuttonized-mime-types}.  The default value is @code{nil}.
This variable is only used when @code{gnus-inhibit-mime-unbuttonizing}
is @code{nil}.

E.g., to see security buttons but no other buttons, you could set this
variable to @code{("multipart/signed")} and leave
@code{gnus-unbuttonized-mime-types} at the default value.

You could also add @code{"multipart/alternative"} to this list to
display radio buttons that allow you to choose one of two media types
those mails include.  See also @code{mm-discouraged-alternatives}
(@pxref{Display Customization, ,Display Customization, emacs-mime, The
Emacs MIME Manual}).

@item gnus-inhibit-mime-unbuttonizing
@vindex gnus-inhibit-mime-unbuttonizing
If this is non-@code{nil}, then all @acronym{MIME} parts get buttons.  The
default value is @code{nil}.

@item gnus-article-mime-part-function
@vindex gnus-article-mime-part-function
For each @acronym{MIME} part, this function will be called with the @acronym{MIME}
handle as the parameter.  The function is meant to be used to allow
users to gather information from the article (e.g., add Vcard info to
the bbdb database) or to do actions based on parts (e.g., automatically
save all jpegs into some directory).

Here's an example function the does the latter:

@lisp
(defun my-save-all-jpeg-parts (handle)
  (when (equal (car (mm-handle-type handle)) "image/jpeg")
    (with-temp-buffer
      (insert (mm-get-part handle))
      (write-region (point-min) (point-max)
                    (read-file-name "Save jpeg to: ")))))
(setq gnus-article-mime-part-function
      'my-save-all-jpeg-parts)
@end lisp

@vindex gnus-mime-multipart-functions
@item gnus-mime-multipart-functions
Alist of @acronym{MIME} multipart types and functions to handle them.

@vindex gnus-mime-display-multipart-alternative-as-mixed
@item gnus-mime-display-multipart-alternative-as-mixed
Display "multipart/alternative" parts as "multipart/mixed".

@vindex gnus-mime-display-multipart-related-as-mixed
@item gnus-mime-display-multipart-related-as-mixed
Display "multipart/related" parts as "multipart/mixed".

If displaying @samp{text/html} is discouraged, see
@code{mm-discouraged-alternatives}, images or other material inside a
"multipart/related" part might be overlooked when this variable is
@code{nil}.  @ref{Display Customization, Display Customization, ,
emacs-mime, Emacs-Mime Manual}.

@vindex gnus-mime-display-multipart-as-mixed
@item gnus-mime-display-multipart-as-mixed
Display "multipart" parts as "multipart/mixed".  If @code{t}, it
overrides @code{nil} values of
@code{gnus-mime-display-multipart-alternative-as-mixed} and
@code{gnus-mime-display-multipart-related-as-mixed}.

@vindex mm-file-name-rewrite-functions
@item mm-file-name-rewrite-functions
List of functions used for rewriting file names of @acronym{MIME} parts.
Each function takes a file name as input and returns a file name.

Ready-made functions include@*
@code{mm-file-name-delete-whitespace},
@code{mm-file-name-trim-whitespace},
@code{mm-file-name-collapse-whitespace}, and
@code{mm-file-name-replace-whitespace}.  The later uses the value of
the variable @code{mm-file-name-replace-whitespace} to replace each
whitespace character in a file name with that string; default value
is @code{"_"} (a single underscore).
@findex mm-file-name-delete-whitespace
@findex mm-file-name-trim-whitespace
@findex mm-file-name-collapse-whitespace
@findex mm-file-name-replace-whitespace
@vindex mm-file-name-replace-whitespace

The standard functions @code{capitalize}, @code{downcase},
@code{upcase}, and @code{upcase-initials} may be useful, too.

Everybody knows that whitespace characters in file names are evil,
except those who don't know.  If you receive lots of attachments from
such unenlightened users, you can make live easier by adding

@lisp
(setq mm-file-name-rewrite-functions
      '(mm-file-name-trim-whitespace
        mm-file-name-collapse-whitespace
        mm-file-name-replace-whitespace))
@end lisp

@noindent
to your @file{~/.gnus.el} file.

@end table


@node Charsets
@section Charsets
@cindex charsets

People use different charsets, and we have @acronym{MIME} to let us know what
charsets they use.  Or rather, we wish we had.  Many people use
newsreaders and mailers that do not understand or use @acronym{MIME}, and
just send out messages without saying what character sets they use.  To
help a bit with this, some local news hierarchies have policies that say
what character set is the default.  For instance, the @samp{fj}
hierarchy uses @code{iso-2022-jp}.

@vindex gnus-group-charset-alist
This knowledge is encoded in the @code{gnus-group-charset-alist}
variable, which is an alist of regexps (use the first item to match full
group names) and default charsets to be used when reading these groups.

@vindex gnus-newsgroup-ignored-charsets
In addition, some people do use soi-disant @acronym{MIME}-aware agents that
aren't.  These blithely mark messages as being in @code{iso-8859-1}
even if they really are in @code{koi-8}.  To help here, the
@code{gnus-newsgroup-ignored-charsets} variable can be used.  The
charsets that are listed here will be ignored.  The variable can be
set on a group-by-group basis using the group parameters (@pxref{Group
Parameters}).  The default value is @code{(unknown-8bit x-unknown)},
which includes values some agents insist on having in there.

@vindex gnus-group-posting-charset-alist
When posting, @code{gnus-group-posting-charset-alist} is used to
determine which charsets should not be encoded using the @acronym{MIME}
encodings.  For instance, some hierarchies discourage using
quoted-printable header encoding.

This variable is an alist of regexps and permitted unencoded charsets
for posting.  Each element of the alist has the form @code{(}@var{test
header body-list}@code{)}, where:

@table @var
@item test
is either a regular expression matching the newsgroup header or a
variable to query,
@item header
is the charset which may be left unencoded in the header (@code{nil}
means encode all charsets),
@item body-list
is a list of charsets which may be encoded using 8bit content-transfer
encoding in the body, or one of the special values @code{nil} (always
encode using quoted-printable) or @code{t} (always use 8bit).
@end table

@cindex Russian
@cindex koi8-r
@cindex koi8-u
@cindex iso-8859-5
@cindex coding system aliases
@cindex preferred charset

@xref{Encoding Customization, , Encoding Customization, emacs-mime,
The Emacs MIME Manual}, for additional variables that control which
MIME charsets are used when sending messages.

Other charset tricks that may be useful, although not Gnus-specific:

If there are several @acronym{MIME} charsets that encode the same Emacs
charset, you can choose what charset to use by saying the following:

@lisp
(put-charset-property 'cyrillic-iso8859-5
                      'preferred-coding-system 'koi8-r)
@end lisp

This means that Russian will be encoded using @code{koi8-r} instead of
the default @code{iso-8859-5} @acronym{MIME} charset.

If you want to read messages in @code{koi8-u}, you can cheat and say

@lisp
(define-coding-system-alias 'koi8-u 'koi8-r)
@end lisp

This will almost do the right thing.

And finally, to read charsets like @code{windows-1251}, you can say
something like

@lisp
(codepage-setup 1251)
(define-coding-system-alias 'windows-1251 'cp1251)
@end lisp


@node Article Commands
@section Article Commands

@table @kbd

@item A P
@cindex PostScript
@cindex printing
@kindex A P (Summary)
@vindex gnus-ps-print-hook
@findex gnus-summary-print-article
Generate and print a PostScript image of the article buffer
(@code{gnus-summary-print-article}).  @code{gnus-ps-print-hook} will
be run just before printing the buffer.  An alternative way to print
article is to use Muttprint (@pxref{Saving Articles}).

@item A C
@vindex gnus-fetch-partial-articles
@findex gnus-summary-show-complete-article
If @code{<backend>-fetch-partial-articles} is non-@code{nil}, Gnus will
fetch partial articles, if the backend it fetches them from supports
it.  Currently only @code{nnimap} does.  If you're looking at a
partial article, and want to see the complete article instead, then
the @kbd{A C} command (@code{gnus-summary-show-complete-article}) will
do so.

@end table


@node Summary Sorting
@section Summary Sorting
@cindex summary sorting

You can have the summary buffer sorted in various ways, even though I
can't really see why you'd want that.

@table @kbd

@item C-c C-s C-n
@kindex C-c C-s C-n (Summary)
@findex gnus-summary-sort-by-number
Sort by article number (@code{gnus-summary-sort-by-number}).

@item C-c C-s C-m C-n
@kindex C-c C-s C-n (Summary)
@findex gnus-summary-sort-by-most-recent-number
Sort by most recent article number
(@code{gnus-summary-sort-by-most-recent-number}).

@item C-c C-s C-a
@kindex C-c C-s C-a (Summary)
@findex gnus-summary-sort-by-author
Sort by author (@code{gnus-summary-sort-by-author}).

@item C-c C-s C-t
@kindex C-c C-s C-t (Summary)
@findex gnus-summary-sort-by-recipient
Sort by recipient (@code{gnus-summary-sort-by-recipient}).

@item C-c C-s C-s
@kindex C-c C-s C-s (Summary)
@findex gnus-summary-sort-by-subject
Sort by subject (@code{gnus-summary-sort-by-subject}).

@item C-c C-s C-d
@kindex C-c C-s C-d (Summary)
@findex gnus-summary-sort-by-date
Sort by date (@code{gnus-summary-sort-by-date}).

@item C-c C-s C-m C-d
@kindex C-c C-s C-m C-d (Summary)
@findex gnus-summary-sort-by-most-recent-date
Sort by most recent date (@code{gnus-summary-sort-by-most-recent-date}).

@item C-c C-s C-l
@kindex C-c C-s C-l (Summary)
@findex gnus-summary-sort-by-lines
Sort by lines (@code{gnus-summary-sort-by-lines}).

@item C-c C-s C-c
@kindex C-c C-s C-c (Summary)
@findex gnus-summary-sort-by-chars
Sort by article length (@code{gnus-summary-sort-by-chars}).

@item C-c C-s C-i
@kindex C-c C-s C-i (Summary)
@findex gnus-summary-sort-by-score
Sort by score (@code{gnus-summary-sort-by-score}).

@item C-c C-s C-r
@kindex C-c C-s C-r (Summary)
@findex gnus-summary-sort-by-random
Randomize (@code{gnus-summary-sort-by-random}).

@item C-c C-s C-o
@kindex C-c C-s C-o (Summary)
@findex gnus-summary-sort-by-original
Sort using the default sorting method
(@code{gnus-summary-sort-by-original}).
@end table

These functions will work both when you use threading and when you don't
use threading.  In the latter case, all summary lines will be sorted,
line by line.  In the former case, sorting will be done on a
root-by-root basis, which might not be what you were looking for.  To
toggle whether to use threading, type @kbd{T T} (@pxref{Thread
Commands}).

If a prefix argument if given, the sort order is reversed.


@node Finding the Parent
@section Finding the Parent
@cindex parent articles
@cindex referring articles

@table @kbd
@item ^
@kindex ^ (Summary)
@findex gnus-summary-refer-parent-article
If you'd like to read the parent of the current article, and it is not
displayed in the summary buffer, you might still be able to.  That is,
if the current group is fetched by @acronym{NNTP}, the parent hasn't expired
and the @code{References} in the current article are not mangled, you
can just press @kbd{^} or @kbd{A r}
(@code{gnus-summary-refer-parent-article}).  If everything goes well,
you'll get the parent.  If the parent is already displayed in the
summary buffer, point will just move to this article.

If given a positive numerical prefix, fetch that many articles back into
the ancestry.  If given a negative numerical prefix, fetch just that
ancestor.  So if you say @kbd{3 ^}, Gnus will fetch the parent, the
grandparent and the grandgrandparent of the current article.  If you say
@kbd{-3 ^}, Gnus will only fetch the grandgrandparent of the current
article.

@item A R (Summary)
@findex gnus-summary-refer-references
@kindex A R (Summary)
Fetch all articles mentioned in the @code{References} header of the
article (@code{gnus-summary-refer-references}).

@item A T (Summary)
@findex gnus-summary-refer-thread
@kindex A T (Summary)
Display the full thread where the current article appears
(@code{gnus-summary-refer-thread}).  This command has to fetch all the
headers in the current group to work, so it usually takes a while.  If
you do it often, you may consider setting @code{gnus-fetch-old-headers}
to @code{invisible} (@pxref{Filling In Threads}).  This won't have any
visible effects normally, but it'll make this command work a whole lot
faster.  Of course, it'll make group entry somewhat slow.

@vindex gnus-refer-thread-limit
The @code{gnus-refer-thread-limit} variable says how many old (i.e.,
articles before the first displayed in the current group) headers to
fetch when doing this command.  The default is 200.  If @code{t}, all
the available headers will be fetched.  This variable can be overridden
by giving the @kbd{A T} command a numerical prefix.

@item M-^ (Summary)
@findex gnus-summary-refer-article
@kindex M-^ (Summary)
@cindex Message-ID
@cindex fetching by Message-ID
You can also ask Gnus for an arbitrary article, no matter what group it
belongs to.  @kbd{M-^} (@code{gnus-summary-refer-article}) will ask you
for a @code{Message-ID}, which is one of those long, hard-to-read
thingies that look something like @samp{<38o6up$6f2@@hymir.ifi.uio.no>}.
You have to get it all exactly right.  No fuzzy searches, I'm afraid.

Gnus looks for the @code{Message-ID} in the headers that have already
been fetched, but also tries all the select methods specified by
@code{gnus-refer-article-method} if it is not found.
@end table

@vindex gnus-refer-article-method
If the group you are reading is located on a back end that does not
support fetching by @code{Message-ID} very well (like @code{nnspool}),
you can set @code{gnus-refer-article-method} to an @acronym{NNTP} method.  It
would, perhaps, be best if the @acronym{NNTP} server you consult is the one
updating the spool you are reading from, but that's not really
necessary.

It can also be a list of select methods, as well as the special symbol
@code{current}, which means to use the current select method.  If it
is a list, Gnus will try all the methods in the list until it finds a
match.

Here's an example setting that will first try the current method, and
then ask Google if that fails:

@lisp
(setq gnus-refer-article-method
      '(current
        (nnweb "google" (nnweb-type google))))
@end lisp

Most of the mail back ends support fetching by @code{Message-ID}, but
do not do a particularly excellent job at it.  That is, @code{nnmbox},
@code{nnbabyl}, @code{nnmaildir}, @code{nnml}, are able to locate
articles from any groups, while @code{nnfolder}, and @code{nnimap} are
only able to locate articles that have been posted to the current
group.  @code{nnmh} does not support this at all.

Fortunately, the special @code{nnregistry} back end is able to locate
articles in any groups, regardless of their back end (@pxref{Registry
Article Refer Method, fetching by @code{Message-ID} using the
registry}).

@node Alternative Approaches
@section Alternative Approaches

Different people like to read news using different methods.  This being
Gnus, we offer a small selection of minor modes for the summary buffers.

@menu
* Pick and Read::               First mark articles and then read them.
* Binary Groups::               Auto-decode all articles.
@end menu


@node Pick and Read
@subsection Pick and Read
@cindex pick and read

Some newsreaders (like @code{nn} and, uhm, @code{Netnews} on VM/CMS) use
a two-phased reading interface.  The user first marks in a summary
buffer the articles she wants to read.  Then she starts reading the
articles with just an article buffer displayed.

@findex gnus-pick-mode
@kindex M-x gnus-pick-mode
Gnus provides a summary buffer minor mode that allows
this---@code{gnus-pick-mode}.  This basically means that a few process
mark commands become one-keystroke commands to allow easy marking, and
it provides one additional command for switching to the summary buffer.

Here are the available keystrokes when using pick mode:

@table @kbd
@item .
@kindex . (Pick)
@findex gnus-pick-article-or-thread
Pick the article or thread on the current line
(@code{gnus-pick-article-or-thread}).  If the variable
@code{gnus-thread-hide-subtree} is true, then this key selects the
entire thread when used at the first article of the thread.  Otherwise,
it selects just the article.  If given a numerical prefix, go to that
thread or article and pick it.  (The line number is normally displayed
at the beginning of the summary pick lines.)

@item SPACE
@kindex SPACE (Pick)
@findex gnus-pick-next-page
Scroll the summary buffer up one page (@code{gnus-pick-next-page}).  If
at the end of the buffer, start reading the picked articles.

@item u
@kindex u (Pick)
@findex gnus-pick-unmark-article-or-thread.
Unpick the thread or article
(@code{gnus-pick-unmark-article-or-thread}).  If the variable
@code{gnus-thread-hide-subtree} is true, then this key unpicks the
thread if used at the first article of the thread.  Otherwise it unpicks
just the article.  You can give this key a numerical prefix to unpick
the thread or article at that line.

@item RET
@kindex RET (Pick)
@findex gnus-pick-start-reading
@vindex gnus-pick-display-summary
Start reading the picked articles (@code{gnus-pick-start-reading}).  If
given a prefix, mark all unpicked articles as read first.  If
@code{gnus-pick-display-summary} is non-@code{nil}, the summary buffer
will still be visible when you are reading.

@end table

All the normal summary mode commands are still available in the
pick-mode, with the exception of @kbd{u}.  However @kbd{!} is available
which is mapped to the same function
@code{gnus-summary-tick-article-forward}.

If this sounds like a good idea to you, you could say:

@lisp
(add-hook 'gnus-summary-mode-hook 'gnus-pick-mode)
@end lisp

@vindex gnus-pick-mode-hook
@code{gnus-pick-mode-hook} is run in pick minor mode buffers.

@vindex gnus-mark-unpicked-articles-as-read
If @code{gnus-mark-unpicked-articles-as-read} is non-@code{nil}, mark
all unpicked articles as read.  The default is @code{nil}.

@vindex gnus-summary-pick-line-format
The summary line format in pick mode is slightly different from the
standard format.  At the beginning of each line the line number is
displayed.  The pick mode line format is controlled by the
@code{gnus-summary-pick-line-format} variable (@pxref{Formatting
Variables}).  It accepts the same format specs that
@code{gnus-summary-line-format} does (@pxref{Summary Buffer Lines}).


@node Binary Groups
@subsection Binary Groups
@cindex binary groups

@findex gnus-binary-mode
@kindex M-x gnus-binary-mode
If you spend much time in binary groups, you may grow tired of hitting
@kbd{X u}, @kbd{n}, @kbd{RET} all the time.  @kbd{M-x gnus-binary-mode}
is a minor mode for summary buffers that makes all ordinary Gnus article
selection functions uudecode series of articles and display the result
instead of just displaying the articles the normal way.

@kindex g (Binary)
@findex gnus-binary-show-article
The only way, in fact, to see the actual articles is the @kbd{g}
command, when you have turned on this mode
(@code{gnus-binary-show-article}).

@vindex gnus-binary-mode-hook
@code{gnus-binary-mode-hook} is called in binary minor mode buffers.


@node Tree Display
@section Tree Display
@cindex trees

@vindex gnus-use-trees
If you don't like the normal Gnus summary display, you might try setting
@code{gnus-use-trees} to @code{t}.  This will create (by default) an
additional @dfn{tree buffer}.  You can execute all summary mode commands
in the tree buffer.

There are a few variables to customize the tree display, of course:

@table @code
@item gnus-tree-mode-hook
@vindex gnus-tree-mode-hook
A hook called in all tree mode buffers.

@item gnus-tree-mode-line-format
@vindex gnus-tree-mode-line-format
A format string for the mode bar in the tree mode buffers (@pxref{Mode
Line Formatting}).  The default is @samp{Gnus: %%b %S %Z}.  For a list
of valid specs, @pxref{Summary Buffer Mode Line}.

@item gnus-selected-tree-face
@vindex gnus-selected-tree-face
Face used for highlighting the selected article in the tree buffer.  The
default is @code{modeline}.

@item gnus-tree-line-format
@vindex gnus-tree-line-format
A format string for the tree nodes.  The name is a bit of a misnomer,
though---it doesn't define a line, but just the node.  The default value
is @samp{%(%[%3,3n%]%)}, which displays the first three characters of
the name of the poster.  It is vital that all nodes are of the same
length, so you @emph{must} use @samp{%4,4n}-like specifiers.

Valid specs are:

@table @samp
@item n
The name of the poster.
@item f
The @code{From} header.
@item N
The number of the article.
@item [
The opening bracket.
@item ]
The closing bracket.
@item s
The subject.
@end table

@xref{Formatting Variables}.

Variables related to the display are:

@table @code
@item gnus-tree-brackets
@vindex gnus-tree-brackets
This is used for differentiating between ``real'' articles and
``sparse'' articles.  The format is
@example
((@var{real-open} . @var{real-close})
 (@var{sparse-open} . @var{sparse-close})
 (@var{dummy-open} . @var{dummy-close}))
@end example
and the default is @code{((?[ . ?]) (?( . ?)) (?@{ . ?@}) (?< . ?>))}.

@item gnus-tree-parent-child-edges
@vindex gnus-tree-parent-child-edges
This is a list that contains the characters used for connecting parent
nodes to their children.  The default is @code{(?- ?\\ ?|)}.

@end table

@item gnus-tree-minimize-window
@vindex gnus-tree-minimize-window
If this variable is non-@code{nil}, Gnus will try to keep the tree
buffer as small as possible to allow more room for the other Gnus
windows.  If this variable is a number, the tree buffer will never be
higher than that number.  The default is @code{t}.  Note that if you
have several windows displayed side-by-side in a frame and the tree
buffer is one of these, minimizing the tree window will also resize all
other windows displayed next to it.

You may also wish to add the following hook to keep the window minimized
at all times:

@lisp
(add-hook 'gnus-configure-windows-hook
          'gnus-tree-perhaps-minimize)
@end lisp

@item gnus-generate-tree-function
@vindex gnus-generate-tree-function
@findex gnus-generate-horizontal-tree
@findex gnus-generate-vertical-tree
The function that actually generates the thread tree.  Two predefined
functions are available: @code{gnus-generate-horizontal-tree} and
@code{gnus-generate-vertical-tree} (which is the default).

@end table

Here's an example from a horizontal tree buffer:

@example
@{***@}-(***)-[odd]-[Gun]
     |      \[Jan]
     |      \[odd]-[Eri]
     |      \(***)-[Eri]
     |            \[odd]-[Paa]
     \[Bjo]
     \[Gun]
     \[Gun]-[Jor]
@end example

Here's the same thread displayed in a vertical tree buffer:

@example
@group
@{***@}
  |--------------------------\-----\-----\
(***)                         [Bjo] [Gun] [Gun]
  |--\-----\-----\                          |
[odd] [Jan] [odd] (***)                   [Jor]
  |           |     |--\
[Gun]       [Eri] [Eri] [odd]
                          |
                        [Paa]
@end group
@end example

If you're using horizontal trees, it might be nice to display the trees
side-by-side with the summary buffer.  You could add something like the
following to your @file{~/.gnus.el} file:

@lisp
(setq gnus-use-trees t
      gnus-generate-tree-function 'gnus-generate-horizontal-tree
      gnus-tree-minimize-window nil)
(gnus-add-configuration
 '(article
   (vertical 1.0
             (horizontal 0.25
                         (summary 0.75 point)
                         (tree 1.0))
             (article 1.0))))
@end lisp

@xref{Window Layout}.


@node Mail Group Commands
@section Mail Group Commands
@cindex mail group commands

Some commands only make sense in mail groups.  If these commands are
invalid in the current group, they will raise a hell and let you know.

All these commands (except the expiry and edit commands) use the
process/prefix convention (@pxref{Process/Prefix}).

@table @kbd

@item B e
@kindex B e (Summary)
@findex gnus-summary-expire-articles
@cindex expiring mail
Run all expirable articles in the current group through the expiry
process (@code{gnus-summary-expire-articles}).  That is, delete all
expirable articles in the group that have been around for a while.
(@pxref{Expiring Mail}).

@item B C-M-e
@kindex B C-M-e (Summary)
@findex gnus-summary-expire-articles-now
@cindex expiring mail
Delete all the expirable articles in the group
(@code{gnus-summary-expire-articles-now}).  This means that @strong{all}
articles eligible for expiry in the current group will
disappear forever into that big @file{/dev/null} in the sky.

@item B DEL
@kindex B DEL (Summary)
@cindex deleting mail
@findex gnus-summary-delete-article
@c @icon{gnus-summary-mail-delete}
Delete the mail article.  This is ``delete'' as in ``delete it from your
disk forever and ever, never to return again.'' Use with caution.
(@code{gnus-summary-delete-article}).

@item B m
@kindex B m (Summary)
@cindex move mail
@findex gnus-summary-move-article
@vindex gnus-preserve-marks
Move the article from one mail group to another
(@code{gnus-summary-move-article}).  Marks will be preserved if
@code{gnus-preserve-marks} is non-@code{nil} (which is the default).

@item B c
@kindex B c (Summary)
@cindex copy mail
@findex gnus-summary-copy-article
@c @icon{gnus-summary-mail-copy}
Copy the article from one group (mail group or not) to a mail group
(@code{gnus-summary-copy-article}).  Marks will be preserved if
@code{gnus-preserve-marks} is non-@code{nil} (which is the default).

@item B B
@kindex B B (Summary)
@cindex crosspost mail
@findex gnus-summary-crosspost-article
Crosspost the current article to some other group
(@code{gnus-summary-crosspost-article}).  This will create a new copy of
the article in the other group, and the Xref headers of the article will
be properly updated.

@item B i
@kindex B i (Summary)
@findex gnus-summary-import-article
Import an arbitrary file into the current mail newsgroup
(@code{gnus-summary-import-article}).  You will be prompted for a file
name, a @code{From} header and a @code{Subject} header.

@item B I
@kindex B I (Summary)
@findex gnus-summary-create-article
Create an empty article in the current mail newsgroups
(@code{gnus-summary-create-article}).  You will be prompted for a
@code{From} header and a @code{Subject} header.

@item B r
@kindex B r (Summary)
@findex gnus-summary-respool-article
@vindex gnus-summary-respool-default-method
Respool the mail article (@code{gnus-summary-respool-article}).
@code{gnus-summary-respool-default-method} will be used as the default
select method when respooling.  This variable is @code{nil} by default,
which means that the current group select method will be used instead.
Marks will be preserved if @code{gnus-preserve-marks} is non-@code{nil}
(which is the default).

@item B w
@itemx e
@kindex B w (Summary)
@kindex e (Summary)
@findex gnus-summary-edit-article
@kindex C-c C-c (Article)
@findex gnus-summary-edit-article-done
Edit the current article (@code{gnus-summary-edit-article}).  To finish
editing and make the changes permanent, type @kbd{C-c C-c}
(@code{gnus-summary-edit-article-done}).  If you give a prefix to the
@kbd{C-c C-c} command, Gnus won't re-highlight the article.

@item B q
@kindex B q (Summary)
@findex gnus-summary-respool-query
If you want to re-spool an article, you might be curious as to what group
the article will end up in before you do the re-spooling.  This command
will tell you (@code{gnus-summary-respool-query}).

@item B t
@kindex B t (Summary)
@findex gnus-summary-respool-trace
Similarly, this command will display all fancy splitting patterns used
when respooling, if any (@code{gnus-summary-respool-trace}).

@item B p
@kindex B p (Summary)
@findex gnus-summary-article-posted-p
Some people have a tendency to send you ``courtesy'' copies when they
follow up to articles you have posted.  These usually have a
@code{Newsgroups} header in them, but not always.  This command
(@code{gnus-summary-article-posted-p}) will try to fetch the current
article from your news server (or rather, from
@code{gnus-refer-article-method} or @code{gnus-select-method}) and will
report back whether it found the article or not.  Even if it says that
it didn't find the article, it may have been posted anyway---mail
propagation is much faster than news propagation, and the news copy may
just not have arrived yet.

@item K E
@kindex K E (Summary)
@findex gnus-article-encrypt-body
@vindex gnus-article-encrypt-protocol
Encrypt the body of an article (@code{gnus-article-encrypt-body}).
The body is encrypted with the encryption protocol specified by the
variable @code{gnus-article-encrypt-protocol}.

@end table

@vindex gnus-move-split-methods
@cindex moving articles
If you move (or copy) articles regularly, you might wish to have Gnus
suggest where to put the articles.  @code{gnus-move-split-methods} is a
variable that uses the same syntax as @code{gnus-split-methods}
(@pxref{Saving Articles}).  You may customize that variable to create
suggestions you find reasonable.  (Note that
@code{gnus-move-split-methods} uses group names where
@code{gnus-split-methods} uses file names.)

@lisp
(setq gnus-move-split-methods
      '(("^From:.*Lars Magne" "nnml:junk")
        ("^Subject:.*gnus" "nnfolder:important")
        (".*" "nnml:misc")))
@end lisp


@node Various Summary Stuff
@section Various Summary Stuff

@menu
* Summary Group Information::   Information oriented commands.
* Searching for Articles::      Multiple article commands.
* Summary Generation Commands::
* Really Various Summary Commands::  Those pesky non-conformant commands.
@end menu

@table @code
@vindex gnus-summary-display-while-building
@item gnus-summary-display-while-building
If non-@code{nil}, show and update the summary buffer as it's being
built.  If @code{t}, update the buffer after every line is inserted.
If the value is an integer, @var{n}, update the display every @var{n}
lines.  The default is @code{nil}.

@vindex gnus-summary-display-arrow
@item gnus-summary-display-arrow
If non-@code{nil}, display an arrow in the fringe to indicate the
current article.

@vindex gnus-summary-mode-hook
@item gnus-summary-mode-hook
This hook is called when creating a summary mode buffer.

@vindex gnus-summary-generate-hook
@item gnus-summary-generate-hook
This is called as the last thing before doing the threading and the
generation of the summary buffer.  It's quite convenient for customizing
the threading variables based on what data the newsgroup has.  This hook
is called from the summary buffer after most summary buffer variables
have been set.

@vindex gnus-summary-prepare-hook
@item gnus-summary-prepare-hook
It is called after the summary buffer has been generated.  You might use
it to, for instance, highlight lines or modify the look of the buffer in
some other ungodly manner.  I don't care.

@vindex gnus-summary-prepared-hook
@item gnus-summary-prepared-hook
A hook called as the very last thing after the summary buffer has been
generated.

@vindex gnus-summary-ignore-duplicates
@item gnus-summary-ignore-duplicates
When Gnus discovers two articles that have the same @code{Message-ID},
it has to do something drastic.  No articles are allowed to have the
same @code{Message-ID}, but this may happen when reading mail from some
sources.  Gnus allows you to customize what happens with this variable.
If it is @code{nil} (which is the default), Gnus will rename the
@code{Message-ID} (for display purposes only) and display the article as
any other article.  If this variable is @code{t}, it won't display the
article---it'll be as if it never existed.

@vindex gnus-alter-articles-to-read-function
@item gnus-alter-articles-to-read-function
This function, which takes two parameters (the group name and the list
of articles to be selected), is called to allow the user to alter the
list of articles to be selected.

For instance, the following function adds the list of cached articles to
the list in one particular group:

@lisp
(defun my-add-cached-articles (group articles)
  (if (string= group "some.group")
      (append gnus-newsgroup-cached articles)
    articles))
@end lisp

@vindex gnus-newsgroup-variables
@item gnus-newsgroup-variables
A list of newsgroup (summary buffer) local variables, or cons of
variables and their default expressions to be evalled (when the default
values are not @code{nil}), that should be made global while the summary
buffer is active.

Note: The default expressions will be evaluated (using function
@code{eval}) before assignment to the local variable rather than just
assigned to it.  If the default expression is the symbol @code{global},
that symbol will not be evaluated but the global value of the local
variable will be used instead.

These variables can be used to set variables in the group parameters
while still allowing them to affect operations done in other
buffers.  For example:

@lisp
(setq gnus-newsgroup-variables
      '(message-use-followup-to
        (gnus-visible-headers .
 "^From:\\|^Newsgroups:\\|^Subject:\\|^Date:\\|^To:")))
@end lisp

Also @pxref{Group Parameters}.

@end table


@node Summary Group Information
@subsection Summary Group Information

@table @kbd

@item H d
@kindex H d (Summary)
@findex gnus-summary-describe-group
Give a brief description of the current group
(@code{gnus-summary-describe-group}).  If given a prefix, force
rereading the description from the server.

@item H h
@kindex H h (Summary)
@findex gnus-summary-describe-briefly
Give an extremely brief description of the most important summary
keystrokes (@code{gnus-summary-describe-briefly}).

@item H i
@kindex H i (Summary)
@findex gnus-info-find-node
Go to the Gnus info node (@code{gnus-info-find-node}).
@end table


@node Searching for Articles
@subsection Searching for Articles

@table @kbd

@item M-s
@kindex M-s (Summary)
@findex gnus-summary-search-article-forward
Search through all subsequent (raw) articles for a regexp
(@code{gnus-summary-search-article-forward}).

@item M-r
@kindex M-r (Summary)
@findex gnus-summary-search-article-backward
Search through all previous (raw) articles for a regexp
(@code{gnus-summary-search-article-backward}).

@item M-S
@kindex M-S (Summary)
@findex gnus-summary-repeat-search-article-forward
Repeat the previous search forwards
(@code{gnus-summary-repeat-search-article-forward}).

@item M-R
@kindex M-R (Summary)
@findex gnus-summary-repeat-search-article-backward
Repeat the previous search backwards
(@code{gnus-summary-repeat-search-article-backward}).

@item &
@kindex & (Summary)
@findex gnus-summary-execute-command
This command will prompt you for a header, a regular expression to match
on this field, and a command to be executed if the match is made
(@code{gnus-summary-execute-command}).  If the header is an empty
string, the match is done on the entire article.  If given a prefix,
search backward instead.

For instance, @kbd{& RET some.*string RET #} will put the process mark on
all articles that have heads or bodies that match @samp{some.*string}.

@item M-&
@kindex M-& (Summary)
@findex gnus-summary-universal-argument
Perform any operation on all articles that have been marked with
the process mark (@code{gnus-summary-universal-argument}).
@end table

@node Summary Generation Commands
@subsection Summary Generation Commands

@table @kbd

@item Y g
@kindex Y g (Summary)
@findex gnus-summary-prepare
Regenerate the current summary buffer (@code{gnus-summary-prepare}).

@item Y c
@kindex Y c (Summary)
@findex gnus-summary-insert-cached-articles
Pull all cached articles (for the current group) into the summary buffer
(@code{gnus-summary-insert-cached-articles}).

@item Y d
@kindex Y d (Summary)
@findex gnus-summary-insert-dormant-articles
Pull all dormant articles (for the current group) into the summary buffer
(@code{gnus-summary-insert-dormant-articles}).

@item Y t
@kindex Y t (Summary)
@findex gnus-summary-insert-ticked-articles
Pull all ticked articles (for the current group) into the summary buffer
(@code{gnus-summary-insert-ticked-articles}).

@end table


@node Really Various Summary Commands
@subsection Really Various Summary Commands

@table @kbd

@item A D
@itemx C-d
@kindex C-d (Summary)
@kindex A D (Summary)
@findex gnus-summary-enter-digest-group
If the current article is a collection of other articles (for instance,
a digest), you might use this command to enter a group based on the that
article (@code{gnus-summary-enter-digest-group}).  Gnus will try to
guess what article type is currently displayed unless you give a prefix
to this command, which forces a ``digest'' interpretation.  Basically,
whenever you see a message that is a collection of other messages of
some format, you @kbd{C-d} and read these messages in a more convenient
fashion.

@vindex gnus-auto-select-on-ephemeral-exit
The variable @code{gnus-auto-select-on-ephemeral-exit} controls what
article should be selected after exiting a digest group.  Valid values
include:

@table @code
@item next
Select the next article.

@item next-unread
Select the next unread article.

@item next-noselect
Move the cursor to the next article.  This is the default.

@item next-unread-noselect
Move the cursor to the next unread article.
@end table

If it has any other value or there is no next (unread) article, the
article selected before entering to the digest group will appear.

@item C-M-d
@kindex C-M-d (Summary)
@findex gnus-summary-read-document
This command is very similar to the one above, but lets you gather
several documents into one biiig group
(@code{gnus-summary-read-document}).  It does this by opening several
@code{nndoc} groups for each document, and then opening an
@code{nnvirtual} group on top of these @code{nndoc} groups.  This
command understands the process/prefix convention
(@pxref{Process/Prefix}).

@item C-t
@kindex C-t (Summary)
@findex gnus-summary-toggle-truncation
Toggle truncation of summary lines
(@code{gnus-summary-toggle-truncation}).  This will probably confuse the
line centering function in the summary buffer, so it's not a good idea
to have truncation switched off while reading articles.

@item =
@kindex = (Summary)
@findex gnus-summary-expand-window
Expand the summary buffer window (@code{gnus-summary-expand-window}).
If given a prefix, force an @code{article} window configuration.

@item C-M-e
@kindex C-M-e (Summary)
@findex gnus-summary-edit-parameters
Edit the group parameters (@pxref{Group Parameters}) of the current
group (@code{gnus-summary-edit-parameters}).

@item C-M-a
@kindex C-M-a (Summary)
@findex gnus-summary-customize-parameters
Customize the group parameters (@pxref{Group Parameters}) of the current
group (@code{gnus-summary-customize-parameters}).

@end table


@node Exiting the Summary Buffer
@section Exiting the Summary Buffer
@cindex summary exit
@cindex exiting groups

Exiting from the summary buffer will normally update all info on the
group and return you to the group buffer.

@table @kbd

@item Z Z
@itemx Z Q
@itemx q
@kindex Z Z (Summary)
@kindex Z Q (Summary)
@kindex q (Summary)
@findex gnus-summary-exit
@vindex gnus-summary-exit-hook
@vindex gnus-summary-prepare-exit-hook
@vindex gnus-group-no-more-groups-hook
@c @icon{gnus-summary-exit}
Exit the current group and update all information on the group
(@code{gnus-summary-exit}).  @code{gnus-summary-prepare-exit-hook} is
called before doing much of the exiting, which calls
@code{gnus-summary-expire-articles} by default.
@code{gnus-summary-exit-hook} is called after finishing the exit
process.  @code{gnus-group-no-more-groups-hook} is run when returning to
group mode having no more (unread) groups.

@item Z E
@itemx Q
@kindex Z E (Summary)
@kindex Q (Summary)
@findex gnus-summary-exit-no-update
Exit the current group without updating any information on the group
(@code{gnus-summary-exit-no-update}).

@item Z c
@itemx c
@kindex Z c (Summary)
@kindex c (Summary)
@findex gnus-summary-catchup-and-exit
@c @icon{gnus-summary-catchup-and-exit}
Mark all unticked articles in the group as read and then exit
(@code{gnus-summary-catchup-and-exit}).

@item Z C
@kindex Z C (Summary)
@findex gnus-summary-catchup-all-and-exit
Mark all articles, even the ticked ones, as read and then exit
(@code{gnus-summary-catchup-all-and-exit}).

@item Z n
@kindex Z n (Summary)
@findex gnus-summary-catchup-and-goto-next-group
Mark all articles as read and go to the next group
(@code{gnus-summary-catchup-and-goto-next-group}).

@item Z p
@kindex Z p (Summary)
@findex gnus-summary-catchup-and-goto-prev-group
Mark all articles as read and go to the previous group
(@code{gnus-summary-catchup-and-goto-prev-group}).

@item Z R
@itemx C-x C-s
@kindex Z R (Summary)
@kindex C-x C-s (Summary)
@findex gnus-summary-reselect-current-group
Exit this group, and then enter it again
(@code{gnus-summary-reselect-current-group}).  If given a prefix, select
all articles, both read and unread.

@item Z G
@itemx M-g
@kindex Z G (Summary)
@kindex M-g (Summary)
@findex gnus-summary-rescan-group
@c @icon{gnus-summary-mail-get}
Exit the group, check for new articles in the group, and select the
group (@code{gnus-summary-rescan-group}).  If given a prefix, select all
articles, both read and unread.

@item Z N
@kindex Z N (Summary)
@findex gnus-summary-next-group
Exit the group and go to the next group
(@code{gnus-summary-next-group}).

@item Z P
@kindex Z P (Summary)
@findex gnus-summary-prev-group
Exit the group and go to the previous group
(@code{gnus-summary-prev-group}).

@item Z s
@kindex Z s (Summary)
@findex gnus-summary-save-newsrc
Save the current number of read/marked articles in the dribble buffer
and then save the dribble buffer (@code{gnus-summary-save-newsrc}).  If
given a prefix, also save the @file{.newsrc} file(s).  Using this
command will make exit without updating (the @kbd{Q} command) worthless.
@end table

@vindex gnus-exit-group-hook
@code{gnus-exit-group-hook} is called when you exit the current group
with an ``updating'' exit.  For instance @kbd{Q}
(@code{gnus-summary-exit-no-update}) does not call this hook.

@findex gnus-summary-wake-up-the-dead
@findex gnus-dead-summary-mode
@vindex gnus-kill-summary-on-exit
If you're in the habit of exiting groups, and then changing your mind
about it, you might set @code{gnus-kill-summary-on-exit} to @code{nil}.
If you do that, Gnus won't kill the summary buffer when you exit it.
(Quelle surprise!)  Instead it will change the name of the buffer to
something like @samp{*Dead Summary ... *} and install a minor mode
called @code{gnus-dead-summary-mode}.  Now, if you switch back to this
buffer, you'll find that all keys are mapped to a function called
@code{gnus-summary-wake-up-the-dead}.  So tapping any keys in a dead
summary buffer will result in a live, normal summary buffer.

There will never be more than one dead summary buffer at any one time.

@vindex gnus-use-cross-reference
The data on the current group will be updated (which articles you have
read, which articles you have replied to, etc.)@: when you exit the
summary buffer.  If the @code{gnus-use-cross-reference} variable is
@code{t} (which is the default), articles that are cross-referenced to
this group and are marked as read, will also be marked as read in the
other subscribed groups they were cross-posted to.  If this variable is
neither @code{nil} nor @code{t}, the article will be marked as read in
both subscribed and unsubscribed groups (@pxref{Crosspost Handling}).


@node Crosspost Handling
@section Crosspost Handling

@cindex velveeta
@cindex spamming
Marking cross-posted articles as read ensures that you'll never have to
read the same article more than once.  Unless, of course, somebody has
posted it to several groups separately.  Posting the same article to
several groups (not cross-posting) is called @dfn{spamming}, and you are
by law required to send nasty-grams to anyone who perpetrates such a
heinous crime.

Remember: Cross-posting is kinda ok, but posting the same article
separately to several groups is not.  Massive cross-posting (aka.
@dfn{velveeta}) is to be avoided at all costs, and you can even use the
@code{gnus-summary-mail-crosspost-complaint} command to complain about
excessive crossposting (@pxref{Summary Mail Commands}).

@cindex cross-posting
@cindex Xref
@cindex @acronym{NOV}
One thing that may cause Gnus to not do the cross-posting thing
correctly is if you use an @acronym{NNTP} server that supports @sc{xover}
(which is very nice, because it speeds things up considerably) which
does not include the @code{Xref} header in its @acronym{NOV} lines.  This is
Evil, but all too common, alas, alack.  Gnus tries to Do The Right Thing
even with @sc{xover} by registering the @code{Xref} lines of all
articles you actually read, but if you kill the articles, or just mark
them as read without reading them, Gnus will not get a chance to snoop
the @code{Xref} lines out of these articles, and will be unable to use
the cross reference mechanism.

@cindex LIST overview.fmt
@cindex overview.fmt
To check whether your @acronym{NNTP} server includes the @code{Xref} header
in its overview files, try @samp{telnet your.nntp.server nntp},
@samp{MODE READER} on @code{inn} servers, and then say @samp{LIST
overview.fmt}.  This may not work, but if it does, and the last line you
get does not read @samp{Xref:full}, then you should shout and whine at
your news admin until she includes the @code{Xref} header in the
overview files.

If you want Gnus to get the @code{Xref}s right all the time, you have to
set @code{nntp-nov-is-evil} to @code{t}, which slows things down
considerably.  Also @pxref{Slow/Expensive Connection}.

C'est la vie.

For an alternative approach, @pxref{Duplicate Suppression}.


@node Duplicate Suppression
@section Duplicate Suppression

By default, Gnus tries to make sure that you don't have to read the same
article more than once by utilizing the crossposting mechanism
(@pxref{Crosspost Handling}).  However, that simple and efficient
approach may not work satisfactory for some users for various
reasons.

@enumerate
@item
The @acronym{NNTP} server may fail to generate the @code{Xref} header.  This
is evil and not very common.

@item
The @acronym{NNTP} server may fail to include the @code{Xref} header in the
@file{.overview} data bases.  This is evil and all too common, alas.

@item
You may be reading the same group (or several related groups) from
different @acronym{NNTP} servers.

@item
You may be getting mail that duplicates articles posted to groups.
@end enumerate

I'm sure there are other situations where @code{Xref} handling fails as
well, but these four are the most common situations.

If, and only if, @code{Xref} handling fails for you, then you may
consider switching on @dfn{duplicate suppression}.  If you do so, Gnus
will remember the @code{Message-ID}s of all articles you have read or
otherwise marked as read, and then, as if by magic, mark them as read
all subsequent times you see them---in @emph{all} groups.  Using this
mechanism is quite likely to be somewhat inefficient, but not overly
so.  It's certainly preferable to reading the same articles more than
once.

Duplicate suppression is not a very subtle instrument.  It's more like a
sledge hammer than anything else.  It works in a very simple
fashion---if you have marked an article as read, it adds this Message-ID
to a cache.  The next time it sees this Message-ID, it will mark the
article as read with the @samp{M} mark.  It doesn't care what group it
saw the article in.

@table @code
@item gnus-suppress-duplicates
@vindex gnus-suppress-duplicates
If non-@code{nil}, suppress duplicates.

@item gnus-save-duplicate-list
@vindex gnus-save-duplicate-list
If non-@code{nil}, save the list of duplicates to a file.  This will
make startup and shutdown take longer, so the default is @code{nil}.
However, this means that only duplicate articles read in a single Gnus
session are suppressed.

@item gnus-duplicate-list-length
@vindex gnus-duplicate-list-length
This variable says how many @code{Message-ID}s to keep in the duplicate
suppression list.  The default is 10000.

@item gnus-duplicate-file
@vindex gnus-duplicate-file
The name of the file to store the duplicate suppression list in.  The
default is @file{~/News/suppression}.
@end table

If you have a tendency to stop and start Gnus often, setting
@code{gnus-save-duplicate-list} to @code{t} is probably a good idea.  If
you leave Gnus running for weeks on end, you may have it @code{nil}.  On
the other hand, saving the list makes startup and shutdown much slower,
so that means that if you stop and start Gnus often, you should set
@code{gnus-save-duplicate-list} to @code{nil}.  Uhm.  I'll leave this up
to you to figure out, I think.

@node Security
@section Security

Gnus is able to verify signed messages or decrypt encrypted messages.
The formats that are supported are @acronym{PGP}, @acronym{PGP/MIME}
and @acronym{S/MIME}, however you need some external programs to get
things to work:

@enumerate
@item
To handle @acronym{PGP} and @acronym{PGP/MIME} messages, you have to
install an OpenPGP implementation such as GnuPG@.  The Lisp interface
to GnuPG included with Emacs is called EasyPG (@pxref{Top, ,EasyPG,
epa, EasyPG Assistant user's manual}), but PGG (@pxref{Top, ,PGG, pgg,
PGG Manual}), and Mailcrypt are also supported.

@item
To handle @acronym{S/MIME} message, you need to install OpenSSL@.  OpenSSL 0.9.6
or newer is recommended.

@end enumerate

The variables that control security functionality on reading/composing
messages include:

@table @code
@item mm-verify-option
@vindex mm-verify-option
Option of verifying signed parts.  @code{never}, not verify;
@code{always}, always verify; @code{known}, only verify known
protocols.  Otherwise, ask user.

@item mm-decrypt-option
@vindex mm-decrypt-option
Option of decrypting encrypted parts.  @code{never}, no decryption;
@code{always}, always decrypt; @code{known}, only decrypt known
protocols.  Otherwise, ask user.

@item mm-sign-option
@vindex mm-sign-option
Option of creating signed parts.  @code{nil}, use default signing
keys; @code{guided}, ask user to select signing keys from the menu.

@item mm-encrypt-option
@vindex mm-encrypt-option
Option of creating encrypted parts.  @code{nil}, use the first
public-key matching the @samp{From:} header as the recipient;
@code{guided}, ask user to select recipient keys from the menu.

@item mml1991-use
@vindex mml1991-use
Symbol indicating elisp interface to OpenPGP implementation for
@acronym{PGP} messages.  The default is @code{epg}, but @code{pgg},
and @code{mailcrypt} are also supported although
deprecated.  By default, Gnus uses the first available interface in
this order.

@item mml2015-use
@vindex mml2015-use
Symbol indicating elisp interface to OpenPGP implementation for
@acronym{PGP/MIME} messages.  The default is @code{epg}, but
@code{pgg}, and @code{mailcrypt} are also supported
although deprecated.  By default, Gnus uses the first available
interface in this order.

@end table

By default the buttons that display security information are not
shown, because they clutter reading the actual e-mail.  You can type
@kbd{K b} manually to display the information.  Use the
@code{gnus-buttonized-mime-types} and
@code{gnus-unbuttonized-mime-types} variables to control this
permanently.  @ref{MIME Commands} for further details, and hints on
how to customize these variables to always display security
information.

@cindex snarfing keys
@cindex importing PGP keys
@cindex PGP key ring import
Snarfing OpenPGP keys (i.e., importing keys from articles into your
key ring) is not supported explicitly through a menu item or command,
rather Gnus do detect and label keys as @samp{application/pgp-keys},
allowing you to specify whatever action you think is appropriate
through the usual @acronym{MIME} infrastructure.  You can use a
@file{~/.mailcap} entry (@pxref{mailcap, , mailcap, emacs-mime, The
Emacs MIME Manual}) such as the following to import keys using GNU
Privacy Guard when you click on the @acronym{MIME} button
(@pxref{Using MIME}).

@example
application/pgp-keys; gpg --import --interactive --verbose; needsterminal
@end example
@noindent
This happens to also be the default action defined in
@code{mailcap-mime-data}.

More information on how to set things for sending outgoing signed and
encrypted messages up can be found in the message manual
(@pxref{Security, ,Security, message, Message Manual}).

@node Mailing List
@section Mailing List
@cindex mailing list
@cindex RFC 2396

@kindex A M (summary)
@findex gnus-mailing-list-insinuate
Gnus understands some mailing list fields of RFC 2369.  To enable it,
add a @code{to-list} group parameter (@pxref{Group Parameters}),
possibly using @kbd{A M} (@code{gnus-mailing-list-insinuate}) in the
summary buffer.

That enables the following commands to the summary buffer:

@table @kbd

@item C-c C-n h
@kindex C-c C-n h (Summary)
@findex gnus-mailing-list-help
Send a message to fetch mailing list help, if List-Help field exists.

@item C-c C-n s
@kindex C-c C-n s (Summary)
@findex gnus-mailing-list-subscribe
Send a message to subscribe the mailing list, if List-Subscribe field exists.

@item C-c C-n u
@kindex C-c C-n u (Summary)
@findex gnus-mailing-list-unsubscribe
Send a message to unsubscribe the mailing list, if List-Unsubscribe
field exists.

@item C-c C-n p
@kindex C-c C-n p (Summary)
@findex gnus-mailing-list-post
Post to the mailing list, if List-Post field exists.

@item C-c C-n o
@kindex C-c C-n o (Summary)
@findex gnus-mailing-list-owner
Send a message to the mailing list owner, if List-Owner field exists.

@item C-c C-n a
@kindex C-c C-n a (Summary)
@findex gnus-mailing-list-archive
Browse the mailing list archive, if List-Archive field exists.

@end table


@node Article Buffer
@chapter Article Buffer
@cindex article buffer

The articles are displayed in the article buffer, of which there is only
one.  All the summary buffers share the same article buffer unless you
tell Gnus otherwise.

@menu
* Hiding Headers::              Deciding what headers should be displayed.
* Using MIME::                  Pushing articles through @acronym{MIME} before reading them.
* HTML::                        Reading @acronym{HTML} messages.
* Customizing Articles::        Tailoring the look of the articles.
* Article Keymap::              Keystrokes available in the article buffer.
* Misc Article::                Other stuff.
@end menu


@node Hiding Headers
@section Hiding Headers
@cindex hiding headers
@cindex deleting headers

The top section of each article is the @dfn{head}.  (The rest is the
@dfn{body}, but you may have guessed that already.)

@vindex gnus-show-all-headers
There is a lot of useful information in the head: the name of the person
who wrote the article, the date it was written and the subject of the
article.  That's well and nice, but there's also lots of information
most people do not want to see---what systems the article has passed
through before reaching you, the @code{Message-ID}, the
@code{References}, etc. ad nauseam---and you'll probably want to get rid
of some of those lines.  If you want to keep all those lines in the
article buffer, you can set @code{gnus-show-all-headers} to @code{t}.

Gnus provides you with two variables for sifting headers:

@table @code

@item gnus-visible-headers
@vindex gnus-visible-headers
If this variable is non-@code{nil}, it should be a regular expression
that says what headers you wish to keep in the article buffer.  All
headers that do not match this variable will be hidden.

For instance, if you only want to see the name of the person who wrote
the article and the subject, you'd say:

@lisp
(setq gnus-visible-headers "^From:\\|^Subject:")
@end lisp

This variable can also be a list of regexps to match headers to
remain visible.

@item gnus-ignored-headers
@vindex gnus-ignored-headers
This variable is the reverse of @code{gnus-visible-headers}.  If this
variable is set (and @code{gnus-visible-headers} is @code{nil}), it
should be a regular expression that matches all lines that you want to
hide.  All lines that do not match this variable will remain visible.

For instance, if you just want to get rid of the @code{References} line
and the @code{Xref} line, you might say:

@lisp
(setq gnus-ignored-headers "^References:\\|^Xref:")
@end lisp

This variable can also be a list of regexps to match headers to
be removed.

Note that if @code{gnus-visible-headers} is non-@code{nil}, this
variable will have no effect.

@end table

@vindex gnus-sorted-header-list
Gnus can also sort the headers for you.  (It does this by default.)  You
can control the sorting by setting the @code{gnus-sorted-header-list}
variable.  It is a list of regular expressions that says in what order
the headers are to be displayed.

For instance, if you want the name of the author of the article first,
and then the subject, you might say something like:

@lisp
(setq gnus-sorted-header-list '("^From:" "^Subject:"))
@end lisp

Any headers that are to remain visible, but are not listed in this
variable, will be displayed in random order after all the headers listed in this variable.

@findex gnus-article-hide-boring-headers
@vindex gnus-boring-article-headers
You can hide further boring headers by setting
@code{gnus-treat-hide-boring-headers} to @code{head}.  What this function
does depends on the @code{gnus-boring-article-headers} variable.  It's a
list, but this list doesn't actually contain header names.  Instead it
lists various @dfn{boring conditions} that Gnus can check and remove
from sight.

These conditions are:
@table @code
@item empty
Remove all empty headers.
@item followup-to
Remove the @code{Followup-To} header if it is identical to the
@code{Newsgroups} header.
@item reply-to
Remove the @code{Reply-To} header if it lists the same addresses as
the @code{From} header, or if the @code{broken-reply-to} group
parameter is set.
@item newsgroups
Remove the @code{Newsgroups} header if it only contains the current group
name.
@item to-address
Remove the @code{To} header if it only contains the address identical to
the current group's @code{to-address} parameter.
@item to-list
Remove the @code{To} header if it only contains the address identical to
the current group's @code{to-list} parameter.
@item cc-list
Remove the @code{Cc} header if it only contains the address identical to
the current group's @code{to-list} parameter.
@item date
Remove the @code{Date} header if the article is less than three days
old.
@item long-to
Remove the @code{To} and/or @code{Cc} header if it is very long.
@item many-to
Remove all @code{To} and/or @code{Cc} headers if there are more than one.
@end table

To include these three elements, you could say something like:

@lisp
(setq gnus-boring-article-headers
      '(empty followup-to reply-to))
@end lisp

This is also the default value for this variable.


@node Using MIME
@section Using MIME
@cindex @acronym{MIME}

Mime is a standard for waving your hands through the air, aimlessly,
while people stand around yawning.

@acronym{MIME}, however, is a standard for encoding your articles, aimlessly,
while all newsreaders die of fear.

@acronym{MIME} may specify what character set the article uses, the encoding
of the characters, and it also makes it possible to embed pictures and
other naughty stuff in innocent-looking articles.

@vindex gnus-display-mime-function
@findex gnus-display-mime
Gnus pushes @acronym{MIME} articles through @code{gnus-display-mime-function}
to display the @acronym{MIME} parts.  This is @code{gnus-display-mime} by
default, which creates a bundle of clickable buttons that can be used to
display, save and manipulate the @acronym{MIME} objects.

The following commands are available when you have placed point over a
@acronym{MIME} button:

@table @kbd
@findex gnus-article-press-button
@item RET (Article)
@kindex RET (Article)
@itemx BUTTON-2 (Article)
Toggle displaying of the @acronym{MIME} object
(@code{gnus-article-press-button}).  If built-in viewers can not display
the object, Gnus resorts to external viewers in the @file{mailcap}
files.  If a viewer has the @samp{copiousoutput} specification, the
object is displayed inline.

@findex gnus-mime-view-part
@item M-RET (Article)
@kindex M-RET (Article)
@itemx v (Article)
Prompt for a method, and then view the @acronym{MIME} object using this
method (@code{gnus-mime-view-part}).

@findex gnus-mime-view-part-as-type
@item t (Article)
@kindex t (Article)
View the @acronym{MIME} object as if it were a different @acronym{MIME} media type
(@code{gnus-mime-view-part-as-type}).

@findex gnus-mime-view-part-as-charset
@item C (Article)
@kindex C (Article)
Prompt for a charset, and then view the @acronym{MIME} object using this
charset (@code{gnus-mime-view-part-as-charset}).

@findex gnus-mime-save-part
@item o (Article)
@kindex o (Article)
Prompt for a file name, and then save the @acronym{MIME} object
(@code{gnus-mime-save-part}).

@findex gnus-mime-save-part-and-strip
@item C-o (Article)
@kindex C-o (Article)
Prompt for a file name, then save the @acronym{MIME} object and strip it from
the article.  Then proceed to article editing, where a reasonable
suggestion is being made on how the altered article should look
like.  The stripped @acronym{MIME} object will be referred via the
message/external-body @acronym{MIME} type.
(@code{gnus-mime-save-part-and-strip}).

@findex gnus-mime-replace-part
@item r (Article)
@kindex r (Article)
Prompt for a file name, replace the @acronym{MIME} object with an
external body referring to the file via the message/external-body
@acronym{MIME} type.  (@code{gnus-mime-replace-part}).

@findex gnus-mime-delete-part
@item d (Article)
@kindex d (Article)
Delete the @acronym{MIME} object from the article and replace it with some
information about the removed @acronym{MIME} object
(@code{gnus-mime-delete-part}).

@c FIXME: gnus-auto-select-part should be documented here

@findex gnus-mime-copy-part
@item c (Article)
@kindex c (Article)
Copy the @acronym{MIME} object to a fresh buffer and display this buffer
(@code{gnus-mime-copy-part}).  If given a prefix, copy the raw contents
without decoding.  If given a numerical prefix, you can do semi-manual
charset stuff (see @code{gnus-summary-show-article-charset-alist} in
@ref{Paging the Article}).  Compressed files like @file{.gz} and
@file{.bz2} are automatically decompressed if
@code{auto-compression-mode} is enabled (@pxref{Compressed Files,,
Accessing Compressed Files, emacs, The Emacs Editor}).

@findex gnus-mime-print-part
@item p (Article)
@kindex p (Article)
Print the @acronym{MIME} object (@code{gnus-mime-print-part}).  This
command respects the @samp{print=} specifications in the
@file{.mailcap} file.

@findex gnus-mime-inline-part
@item i (Article)
@kindex i (Article)
Insert the contents of the @acronym{MIME} object into the buffer
(@code{gnus-mime-inline-part}) as @samp{text/plain}.  If given a prefix, insert
the raw contents without decoding.  If given a numerical prefix, you can
do semi-manual charset stuff (see
@code{gnus-summary-show-article-charset-alist} in @ref{Paging the
Article}).  Compressed files like @file{.gz} and @file{.bz2} are
automatically decompressed depending on @code{jka-compr} regardless of
@code{auto-compression-mode} (@pxref{Compressed Files,, Accessing
Compressed Files, emacs, The Emacs Editor}).

@findex gnus-mime-view-part-internally
@item E (Article)
@kindex E (Article)
View the @acronym{MIME} object with an internal viewer.  If no internal
viewer is available, use an external viewer
(@code{gnus-mime-view-part-internally}).

@findex gnus-mime-view-part-externally
@item e (Article)
@kindex e (Article)
View the @acronym{MIME} object with an external viewer.
(@code{gnus-mime-view-part-externally}).

@findex gnus-mime-pipe-part
@item | (Article)
@kindex | (Article)
Output the @acronym{MIME} object to a process (@code{gnus-mime-pipe-part}).

@findex gnus-mime-action-on-part
@item . (Article)
@kindex . (Article)
Interactively run an action on the @acronym{MIME} object
(@code{gnus-mime-action-on-part}).

@end table

Gnus will display some @acronym{MIME} objects automatically.  The way Gnus
determines which parts to do this with is described in the Emacs
@acronym{MIME} manual.

It might be best to just use the toggling functions from the article
buffer to avoid getting nasty surprises.  (For instance, you enter the
group @samp{alt.sing-a-long} and, before you know it, @acronym{MIME} has
decoded the sound file in the article and some horrible sing-a-long song
comes screaming out your speakers, and you can't find the volume button,
because there isn't one, and people are starting to look at you, and you
try to stop the program, but you can't, and you can't find the program
to control the volume, and everybody else in the room suddenly decides
to look at you disdainfully, and you'll feel rather stupid.)

Any similarity to real events and people is purely coincidental.  Ahem.

Also @pxref{MIME Commands}.


@node HTML
@section @acronym{HTML}
@cindex @acronym{HTML}

If you have @code{w3m} installed on your system, Gnus can display
@acronym{HTML} articles in the article buffer.  There are many Gnus
add-ons for doing this, using various approaches, but there's one
(sort of) built-in method that's used by default.

For a complete overview, consult @xref{Display Customization,
,Display Customization, emacs-mime, The Emacs MIME Manual}.  This
section only describes the default method.

@table @code
@item mm-text-html-renderer
@vindex mm-text-html-renderer
If set to @code{gnus-article-html}, Gnus will use the built-in method,
that's based on @code{w3m}.

@item gnus-blocked-images
@vindex gnus-blocked-images
External images that have @acronym{URL}s that match this regexp won't
be fetched and displayed.  For instance, do block all @acronym{URL}s
that have the string ``ads'' in them, do the following:

@lisp
(setq gnus-blocked-images "ads")
@end lisp

This can also be a function to be evaluated.  If so, it will be
called with the group name as the parameter.  The default value is
@code{gnus-block-private-groups}, which will return @samp{"."} for
anything that isn't a newsgroup.  This means that no external images
will be fetched as a result of reading mail, so that nobody can use
web bugs (and the like) to track whether you've read email.

Also @pxref{Misc Article} for @code{gnus-inhibit-images}.

@item gnus-html-cache-directory
@vindex gnus-html-cache-directory
Gnus will download and cache images according to how
@code{gnus-blocked-images} is set.  These images will be stored in
this directory.

@item gnus-html-cache-size
@vindex gnus-html-cache-size
When @code{gnus-html-cache-size} bytes have been used in that
directory, the oldest files will be deleted.  The default is 500MB.

@item gnus-html-frame-width
@vindex gnus-html-frame-width
The width to use when rendering HTML@.  The default is 70.

@item gnus-max-image-proportion
@vindex gnus-max-image-proportion
How big pictures displayed are in relation to the window they're in.
A value of 0.7 (the default) means that they are allowed to take up
70% of the width and height of the window.  If they are larger than
this, and Emacs supports it, then the images will be rescaled down to
fit these criteria.

@end table

To use this, make sure that you have @code{w3m} and @code{curl}
installed.  If you have, then Gnus should display @acronym{HTML}
automatically.



@node Customizing Articles
@section Customizing Articles
@cindex article customization

A slew of functions for customizing how the articles are to look like
exist.  You can call these functions interactively
(@pxref{Article Washing}), or you can have them
called automatically when you select the articles.

To have them called automatically, you should set the corresponding
``treatment'' variable.  For instance, to have headers hidden, you'd set
@code{gnus-treat-hide-headers}.  Below is a list of variables that can
be set, but first we discuss the values these variables can have.

Note: Some values, while valid, make little sense.  Check the list below
for sensible values.

@enumerate
@item
@code{nil}: Don't do this treatment.

@item
@code{t}: Do this treatment on all body parts.

@item
@code{head}: Do the treatment on the headers.

@item
@code{first}: Do this treatment on the first body part.

@item
@code{last}: Do this treatment on the last body part.

@item
An integer: Do this treatment on all body parts that have a length less
than this number.

@item
A list of strings: Do this treatment on all body parts that are in
articles that are read in groups that have names that match one of the
regexps in the list.

@item
A list where the first element is not a string:

The list is evaluated recursively.  The first element of the list is a
predicate.  The following predicates are recognized: @code{or},
@code{and}, @code{not} and @code{typep}.  Here's an example:

@lisp
(or last
    (typep "text/x-vcard"))
@end lisp

@end enumerate

You may have noticed that the word @dfn{part} is used here.  This refers
to the fact that some messages are @acronym{MIME} multipart articles that may
be divided into several parts.  Articles that are not multiparts are
considered to contain just a single part.

@vindex gnus-article-treat-types
Are the treatments applied to all sorts of multipart parts?  Yes, if you
want to, but by default, only @samp{text/plain} parts are given the
treatment.  This is controlled by the @code{gnus-article-treat-types}
variable, which is a list of regular expressions that are matched to the
type of the part.  This variable is ignored if the value of the
controlling variable is a predicate list, as described above.

@ifinfo
@c Avoid sort of redundant entries in the same section for the printed
@c manual, but add them in info to allow `i gnus-treat-foo-bar RET' or
@c `i foo-bar'.
@vindex gnus-treat-buttonize
@vindex gnus-treat-buttonize-head
@vindex gnus-treat-capitalize-sentences
@vindex gnus-treat-overstrike
@vindex gnus-treat-strip-cr
@vindex gnus-treat-strip-headers-in-body
@vindex gnus-treat-strip-leading-blank-lines
@vindex gnus-treat-strip-multiple-blank-lines
@vindex gnus-treat-strip-pem
@vindex gnus-treat-strip-trailing-blank-lines
@vindex gnus-treat-unsplit-urls
@vindex gnus-treat-wash-html
@vindex gnus-treat-date
@vindex gnus-treat-from-picon
@vindex gnus-treat-mail-picon
@vindex gnus-treat-newsgroups-picon
@vindex gnus-treat-from-gravatar
@vindex gnus-treat-mail-gravatar
@vindex gnus-treat-display-smileys
@vindex gnus-treat-body-boundary
@vindex gnus-treat-display-x-face
@vindex gnus-treat-display-face
@vindex gnus-treat-emphasize
@vindex gnus-treat-fill-article
@vindex gnus-treat-fill-long-lines
@vindex gnus-treat-hide-boring-headers
@vindex gnus-treat-hide-citation
@vindex gnus-treat-hide-citation-maybe
@vindex gnus-treat-hide-headers
@vindex gnus-treat-hide-signature
@vindex gnus-treat-strip-banner
@vindex gnus-treat-strip-list-identifiers
@vindex gnus-treat-highlight-citation
@vindex gnus-treat-highlight-headers
@vindex gnus-treat-highlight-signature
@vindex gnus-treat-play-sounds
@vindex gnus-treat-x-pgp-sig
@vindex gnus-treat-unfold-headers
@vindex gnus-treat-fold-headers
@vindex gnus-treat-fold-newsgroups
@vindex gnus-treat-leading-whitespace
@end ifinfo

The following treatment options are available.  The easiest way to
customize this is to examine the @code{gnus-article-treat} customization
group.  Values in parenthesis are suggested sensible values.  Others are
possible but those listed are probably sufficient for most people.

@table @code
@item gnus-treat-buttonize (t, integer)
@item gnus-treat-buttonize-head (head)

@xref{Article Buttons}.

@item gnus-treat-capitalize-sentences (t, integer)
@item gnus-treat-overstrike (t, integer)
@item gnus-treat-strip-cr (t, integer)
@item gnus-treat-strip-headers-in-body (t, integer)
@item gnus-treat-strip-leading-blank-lines (t, first, integer)
@item gnus-treat-strip-multiple-blank-lines (t, integer)
@item gnus-treat-strip-pem (t, last, integer)
@item gnus-treat-strip-trailing-blank-lines (t, last, integer)
@item gnus-treat-unsplit-urls (t, integer)
@item gnus-treat-wash-html (t, integer)

@xref{Article Washing}.

@item gnus-treat-date (head)

This will transform/add date headers according to the
@code{gnus-article-date-headers} variable.  This is a list of Date
headers to display.  The formats available are:

@table @code
@item ut
Universal time, aka GMT, aka ZULU.

@item local
The user's local time zone.

@item english
A semi-readable English sentence.

@item lapsed
The time elapsed since the message was posted.

@item combined-lapsed
Both the original date header and a (shortened) elapsed time.

@item original
The original date header.

@item iso8601
ISO8601 format, i.e., ``2010-11-23T22:05:21''.

@item user-defined
A format done according to the @code{gnus-article-time-format}
variable.

@end table

@xref{Article Date}.

@item gnus-treat-from-picon (head)
@item gnus-treat-mail-picon (head)
@item gnus-treat-newsgroups-picon (head)

@xref{Picons}.

@item gnus-treat-from-gravatar (head)
@item gnus-treat-mail-gravatar (head)

@xref{Gravatars}.

@item gnus-treat-display-smileys (t, integer)

@item gnus-treat-body-boundary (head)

@vindex gnus-body-boundary-delimiter
Adds a delimiter between header and body, the string used as delimiter
is controlled by @code{gnus-body-boundary-delimiter}.

@xref{Smileys}.

@vindex gnus-treat-display-x-face
@item gnus-treat-display-x-face (head)

@xref{X-Face}.

@vindex gnus-treat-display-face
@item gnus-treat-display-face (head)

@xref{Face}.

@vindex gnus-treat-emphasize
@item gnus-treat-emphasize (t, head, integer)
@vindex gnus-treat-fill-article
@item gnus-treat-fill-article (t, integer)
@vindex gnus-treat-fill-long-lines
@item gnus-treat-fill-long-lines (t, integer)
@vindex gnus-treat-hide-boring-headers
@item gnus-treat-hide-boring-headers (head)
@vindex gnus-treat-hide-citation
@item gnus-treat-hide-citation (t, integer)
@vindex gnus-treat-hide-citation-maybe
@item gnus-treat-hide-citation-maybe (t, integer)
@vindex gnus-treat-hide-headers
@item gnus-treat-hide-headers (head)
@vindex gnus-treat-hide-signature
@item gnus-treat-hide-signature (t, last)
@vindex gnus-treat-strip-banner
@item gnus-treat-strip-banner (t, last)
@vindex gnus-treat-strip-list-identifiers
@item gnus-treat-strip-list-identifiers (head)

@xref{Article Hiding}.

@vindex gnus-treat-highlight-citation
@item gnus-treat-highlight-citation (t, integer)
@vindex gnus-treat-highlight-headers
@item gnus-treat-highlight-headers (head)
@vindex gnus-treat-highlight-signature
@item gnus-treat-highlight-signature (t, last, integer)

@xref{Article Highlighting}.

@vindex gnus-treat-play-sounds
@item gnus-treat-play-sounds
@item gnus-treat-ansi-sequences (t)
@vindex gnus-treat-x-pgp-sig
@item gnus-treat-x-pgp-sig (head)

@vindex gnus-treat-unfold-headers
@item gnus-treat-unfold-headers (head)
@vindex gnus-treat-fold-headers
@item gnus-treat-fold-headers (head)
@vindex gnus-treat-fold-newsgroups
@item gnus-treat-fold-newsgroups (head)
@vindex gnus-treat-leading-whitespace
@item gnus-treat-leading-whitespace (head)

@xref{Article Header}.


@end table

@vindex gnus-part-display-hook
You can, of course, write your own functions to be called from
@code{gnus-part-display-hook}.  The functions are called narrowed to the
part, and you can do anything you like, pretty much.  There is no
information that you have to keep in the buffer---you can change
everything.


@node Article Keymap
@section Article Keymap

Most of the keystrokes in the summary buffer can also be used in the
article buffer.  They should behave as if you typed them in the summary
buffer, which means that you don't actually have to have a summary
buffer displayed while reading.  You can do it all from the article
buffer.

@kindex v (Article)
@cindex keys, reserved for users (Article)
The key @kbd{v} is reserved for users.  You can bind it to some
command or better use it as a prefix key.

A few additional keystrokes are available:

@table @kbd

@item SPACE
@kindex SPACE (Article)
@findex gnus-article-next-page
Scroll forwards one page (@code{gnus-article-next-page}).
This is exactly the same as @kbd{h SPACE h}.

@item DEL
@kindex DEL (Article)
@findex gnus-article-prev-page
Scroll backwards one page (@code{gnus-article-prev-page}).
This is exactly the same as @kbd{h DEL h}.

@item C-c ^
@kindex C-c ^ (Article)
@findex gnus-article-refer-article
If point is in the neighborhood of a @code{Message-ID} and you press
@kbd{C-c ^}, Gnus will try to get that article from the server
(@code{gnus-article-refer-article}).

@item C-c C-m
@kindex C-c C-m (Article)
@findex gnus-article-mail
Send a reply to the address near point (@code{gnus-article-mail}).  If
given a prefix, include the mail.

@item s
@kindex s (Article)
@findex gnus-article-show-summary
Reconfigure the buffers so that the summary buffer becomes visible
(@code{gnus-article-show-summary}).

@item ?
@kindex ? (Article)
@findex gnus-article-describe-briefly
Give a very brief description of the available keystrokes
(@code{gnus-article-describe-briefly}).

@item TAB
@kindex TAB (Article)
@findex gnus-article-next-button
Go to the next button, if any (@code{gnus-article-next-button}).  This
only makes sense if you have buttonizing turned on.

@item M-TAB
@kindex M-TAB (Article)
@findex gnus-article-prev-button
Go to the previous button, if any (@code{gnus-article-prev-button}).

@item R
@kindex R (Article)
@findex gnus-article-reply-with-original
Send a reply to the current article and yank the current article
(@code{gnus-article-reply-with-original}).  If the region is active,
only yank the text in the region.

@item S W
@kindex S W (Article)
@findex gnus-article-wide-reply-with-original
Send a wide reply to the current article and yank the current article
(@code{gnus-article-wide-reply-with-original}).  If the region is
active, only yank the text in the region.

@item F
@kindex F (Article)
@findex gnus-article-followup-with-original
Send a followup to the current article and yank the current article
(@code{gnus-article-followup-with-original}).  If the region is active,
only yank the text in the region.


@end table


@node Misc Article
@section Misc Article

@table @code

@item gnus-single-article-buffer
@vindex gnus-single-article-buffer
@cindex article buffers, several
If non-@code{nil}, use the same article buffer for all the groups.
(This is the default.)  If @code{nil}, each group will have its own
article buffer.

@item gnus-widen-article-window
@cindex gnus-widen-article-window
If non-@code{nil}, selecting the article buffer with the @kbd{h}
command will ``widen'' the article window to take the entire frame.

@vindex gnus-article-decode-hook
@item gnus-article-decode-hook
@cindex @acronym{MIME}
Hook used to decode @acronym{MIME} articles.  The default value is
@code{(article-decode-charset article-decode-encoded-words)}

@vindex gnus-article-prepare-hook
@item gnus-article-prepare-hook
This hook is called right after the article has been inserted into the
article buffer.  It is mainly intended for functions that do something
depending on the contents; it should probably not be used for changing
the contents of the article buffer.

@item gnus-article-mode-hook
@vindex gnus-article-mode-hook
Hook called in article mode buffers.

@item gnus-article-mode-syntax-table
@vindex gnus-article-mode-syntax-table
Syntax table used in article buffers.  It is initialized from
@code{text-mode-syntax-table}.

@vindex gnus-article-over-scroll
@item gnus-article-over-scroll
If non-@code{nil}, allow scrolling the article buffer even when there
no more new text to scroll in.  The default is @code{nil}.

@vindex gnus-article-mode-line-format
@item gnus-article-mode-line-format
This variable is a format string along the same lines as
@code{gnus-summary-mode-line-format} (@pxref{Summary Buffer Mode
Line}).  It accepts the same format specifications as that variable,
with two extensions:

@table @samp

@item w
The @dfn{wash status} of the article.  This is a short string with one
character for each possible article wash operation that may have been
performed.  The characters and their meaning:

@table @samp

@item c
Displayed when cited text may be hidden in the article buffer.

@item h
Displayed when headers are hidden in the article buffer.

@item p
Displayed when article is digitally signed or encrypted, and Gnus has
hidden the security headers.  (N.B. does not tell anything about
security status, i.e., good or bad signature.)

@item s
Displayed when the signature has been hidden in the Article buffer.

@item o
Displayed when Gnus has treated overstrike characters in the article buffer.

@item e
Displayed when Gnus has treated emphasized strings in the article buffer.

@end table

@item m
The number of @acronym{MIME} parts in the article.

@end table

@vindex gnus-break-pages

@item gnus-break-pages
Controls whether @dfn{page breaking} is to take place.  If this variable
is non-@code{nil}, the articles will be divided into pages whenever a
page delimiter appears in the article.  If this variable is @code{nil},
paging will not be done.

@item gnus-page-delimiter
@vindex gnus-page-delimiter
This is the delimiter mentioned above.  By default, it is @samp{^L}
(formfeed).

@cindex IDNA
@cindex internationalized domain names
@vindex gnus-use-idna
@item gnus-use-idna
This variable controls whether Gnus performs IDNA decoding of
internationalized domain names inside @samp{From}, @samp{To} and
@samp{Cc} headers.  @xref{IDNA, ,IDNA,message, The Message Manual},
for how to compose such messages.  This requires
@uref{http://www.gnu.org/software/libidn/, GNU Libidn}, and this
variable is only enabled if you have installed it.

@vindex gnus-inhibit-images
@item gnus-inhibit-images
If this is non-@code{nil}, inhibit displaying of images inline in the
article body.  It is effective to images that are in articles as
@acronym{MIME} parts, and images in @acronym{HTML} articles rendered
when @code{mm-text-html-renderer} (@pxref{Display Customization,
,Display Customization, emacs-mime, The Emacs MIME Manual}) is
@code{shr} or @code{gnus-w3m}.

@end table


@node Composing Messages
@chapter Composing Messages
@cindex composing messages
@cindex messages
@cindex mail
@cindex sending mail
@cindex reply
@cindex followup
@cindex post
@cindex using gpg
@cindex using s/mime
@cindex using smime

@kindex C-c C-c (Post)
All commands for posting and mailing will put you in a message buffer
where you can edit the article all you like, before you send the
article by pressing @kbd{C-c C-c}.  @xref{Top, , Overview, message,
Message Manual}.  Where the message will be posted/mailed to depends
on your setup (@pxref{Posting Server}).

@menu
* Mail::                        Mailing and replying.
* Posting Server::              What server should you post and mail via?
* POP before SMTP::             You cannot send a mail unless you read a mail.
* Mail and Post::               Mailing and posting at the same time.
* Archived Messages::           Where Gnus stores the messages you've sent.
* Posting Styles::              An easier way to specify who you are.
* Drafts::                      Postponing messages and rejected messages.
* Rejected Articles::           What happens if the server doesn't like your article?
* Signing and encrypting::      How to compose secure messages.
@end menu

Also @pxref{Canceling and Superseding} for information on how to
remove articles you shouldn't have posted.


@node Mail
@section Mail

Variables for customizing outgoing mail:

@table @code
@item gnus-uu-digest-headers
@vindex gnus-uu-digest-headers
List of regexps to match headers included in digested messages.  The
headers will be included in the sequence they are matched.  If
@code{nil} include all headers.

@item gnus-add-to-list
@vindex gnus-add-to-list
If non-@code{nil}, add a @code{to-list} group parameter to mail groups
that have none when you do a @kbd{a}.

@item gnus-confirm-mail-reply-to-news
@vindex gnus-confirm-mail-reply-to-news
If non-@code{nil}, Gnus will ask you for a confirmation when you are
about to reply to news articles by mail.  If it is @code{nil}, nothing
interferes in what you want to do.  This can also be a function
receiving the group name as the only parameter which should return
non-@code{nil} if a confirmation is needed, or a regular expression
matching group names, where confirmation should be asked for.

If you find yourself never wanting to reply to mail, but occasionally
press @kbd{R} anyway, this variable might be for you.

@item gnus-confirm-treat-mail-like-news
@vindex gnus-confirm-treat-mail-like-news
If non-@code{nil}, Gnus also requests confirmation according to
@code{gnus-confirm-mail-reply-to-news} when replying to mail.  This is
useful for treating mailing lists like newsgroups.

@end table


@node Posting Server
@section Posting Server

When you press those magical @kbd{C-c C-c} keys to ship off your latest
(extremely intelligent, of course) article, where does it go?

Thank you for asking.  I hate you.

It can be quite complicated.

@vindex gnus-post-method
When posting news, Message usually invokes @code{message-send-news}
(@pxref{News Variables, , News Variables, message, Message Manual}).
Normally, Gnus will post using the same select method as you're
reading from (which might be convenient if you're reading lots of
groups from different private servers).  However.  If the server
you're reading from doesn't allow posting, just reading, you probably
want to use some other server to post your (extremely intelligent and
fabulously interesting) articles.  You can then set the
@code{gnus-post-method} to some other method:

@lisp
(setq gnus-post-method '(nnspool ""))
@end lisp

Now, if you've done this, and then this server rejects your article, or
this server is down, what do you do then?  To override this variable you
can use a non-zero prefix to the @kbd{C-c C-c} command to force using
the ``current'' server, to get back the default behavior, for posting.

If you give a zero prefix (i.e., @kbd{C-u 0 C-c C-c}) to that command,
Gnus will prompt you for what method to use for posting.

You can also set @code{gnus-post-method} to a list of select methods.
If that's the case, Gnus will always prompt you for what method to use
for posting.

Finally, if you want to always post using the native select method,
you can set this variable to @code{native}.

@vindex message-send-mail-function
When sending mail, Message invokes the function specified by the
variable @code{message-send-mail-function}.  Gnus tries to set it to a
value suitable for your system.
@xref{Mail Variables, ,Mail Variables,message,Message manual}, for more
information.


@node POP before SMTP
@section POP before SMTP
@cindex pop before smtp
@findex mail-source-touch-pop

Does your @acronym{ISP} use @acronym{POP}-before-@acronym{SMTP}
authentication?  This authentication method simply requires you to
contact the @acronym{POP} server before sending email.  To do that,
put the following lines in your @file{~/.gnus.el} file:

@lisp
(add-hook 'message-send-mail-hook 'mail-source-touch-pop)
@end lisp

@noindent
The @code{mail-source-touch-pop} function does @acronym{POP}
authentication according to the value of @code{mail-sources} without
fetching mails, just before sending a mail.  @xref{Mail Sources}.

If you have two or more @acronym{POP} mail servers set in
@code{mail-sources}, you may want to specify one of them to
@code{mail-source-primary-source} as the @acronym{POP} mail server to be
used for the @acronym{POP}-before-@acronym{SMTP} authentication.  If it
is your primary @acronym{POP} mail server (i.e., you are fetching mails
mainly from that server), you can set it permanently as follows:

@lisp
(setq mail-source-primary-source
      '(pop :server "pop3.mail.server"
            :password "secret"))
@end lisp

@noindent
Otherwise, bind it dynamically only when performing the
@acronym{POP}-before-@acronym{SMTP} authentication as follows:

@lisp
(add-hook 'message-send-mail-hook
          (lambda ()
            (let ((mail-source-primary-source
                   '(pop :server "pop3.mail.server"
                         :password "secret")))
              (mail-source-touch-pop))))
@end lisp


@node Mail and Post
@section Mail and Post

Here's a list of variables relevant to both mailing and
posting:

@table @code
@item gnus-mailing-list-groups
@findex gnus-mailing-list-groups
@cindex mailing lists

If your news server offers groups that are really mailing lists
gatewayed to the @acronym{NNTP} server, you can read those groups without
problems, but you can't post/followup to them without some difficulty.
One solution is to add a @code{to-address} to the group parameters
(@pxref{Group Parameters}).  An easier thing to do is set the
@code{gnus-mailing-list-groups} to a regexp that matches the groups that
really are mailing lists.  Then, at least, followups to the mailing
lists will work most of the time.  Posting to these groups (@kbd{a}) is
still a pain, though.

@item gnus-user-agent
@vindex gnus-user-agent
@cindex User-Agent

This variable controls which information should be exposed in the
User-Agent header.  It can be a list of symbols or a string.  Valid
symbols are @code{gnus} (show Gnus version) and @code{emacs} (show Emacs
version).  In addition to the Emacs version, you can add @code{codename}
(show (S)XEmacs codename) or either @code{config} (show system
configuration) or @code{type} (show system type).  If you set it to a
string, be sure to use a valid format, see RFC 2616.

@end table

You may want to do spell-checking on messages that you send out.  Or, if
you don't want to spell-check by hand, you could add automatic
spell-checking via the @code{ispell} package:

@cindex ispell
@findex ispell-message
@lisp
(add-hook 'message-send-hook 'ispell-message)
@end lisp

If you want to change the @code{ispell} dictionary based on what group
you're in, you could say something like the following:

@lisp
(add-hook 'gnus-select-group-hook
          (lambda ()
            (cond
             ((string-match
               "^de\\." (gnus-group-real-name gnus-newsgroup-name))
              (ispell-change-dictionary "deutsch"))
             (t
              (ispell-change-dictionary "english")))))
@end lisp

Modify to suit your needs.

@vindex gnus-message-highlight-citation
If @code{gnus-message-highlight-citation} is t, different levels of
citations are highlighted like in Gnus article buffers also in message
mode buffers.

@node Archived Messages
@section Archived Messages
@cindex archived messages
@cindex sent messages

Gnus provides a few different methods for storing the mail and news you
send.  The default method is to use the @dfn{archive virtual server} to
store the messages.  If you want to disable this completely, the
@code{gnus-message-archive-group} variable should be @code{nil}.  The
default is "sent.%Y-%m", which gives you one archive group per month.

For archiving interesting messages in a group you read, see the
@kbd{B c} (@code{gnus-summary-copy-article}) command (@pxref{Mail
Group Commands}).

@vindex gnus-message-archive-method
@code{gnus-message-archive-method} says what virtual server Gnus is to
use to store sent messages.  The default is @code{"archive"}, and when
actually being used it is expanded into:

@lisp
(nnfolder "archive"
          (nnfolder-directory   "~/Mail/archive")
          (nnfolder-active-file "~/Mail/archive/active")
          (nnfolder-get-new-mail nil)
          (nnfolder-inhibit-expiry t))
@end lisp

@quotation
@vindex gnus-update-message-archive-method
Note: a server like this is saved in the @file{~/.newsrc.eld} file first
so that it may be used as a real method of the server which is named
@code{"archive"} (that is, for the case where
@code{gnus-message-archive-method} is set to @code{"archive"}) ever
since.  If it once has been saved, it will never be updated by default
even if you change the value of @code{gnus-message-archive-method}
afterward.  Therefore, the server @code{"archive"} doesn't necessarily
mean the @code{nnfolder} server like this at all times.  If you want the
saved method to reflect always the value of
@code{gnus-message-archive-method}, set the
@code{gnus-update-message-archive-method} variable to a non-@code{nil}
value.  The default value of this variable is @code{nil}.
@end quotation

You can, however, use any mail select method (@code{nnml},
@code{nnmbox}, etc.).  @code{nnfolder} is a quite likable select method
for doing this sort of thing, though.  If you don't like the default
directory chosen, you could say something like:

@lisp
(setq gnus-message-archive-method
      '(nnfolder "archive"
                 (nnfolder-inhibit-expiry t)
                 (nnfolder-active-file "~/News/sent-mail/active")
                 (nnfolder-directory "~/News/sent-mail/")))
@end lisp

@vindex gnus-message-archive-group
@cindex Gcc
Gnus will insert @code{Gcc} headers in all outgoing messages that point
to one or more group(s) on that server.  Which group to use is
determined by the @code{gnus-message-archive-group} variable.

This variable can be used to do the following:

@table @asis
@item a string
Messages will be saved in that group.

Note that you can include a select method in the group name, then the
message will not be stored in the select method given by
@code{gnus-message-archive-method}, but in the select method specified
by the group name, instead.  Suppose @code{gnus-message-archive-method}
has the default value shown above.  Then setting
@code{gnus-message-archive-group} to @code{"foo"} means that outgoing
messages are stored in @samp{nnfolder+archive:foo}, but if you use the
value @code{"nnml:foo"}, then outgoing messages will be stored in
@samp{nnml:foo}.

@item a list of strings
Messages will be saved in all those groups.

@item an alist of regexps, functions and forms
When a key ``matches'', the result is used.

@item @code{nil}
No message archiving will take place.
@end table

Let's illustrate:

Just saving to a single group called @samp{MisK}:
@lisp
(setq gnus-message-archive-group "MisK")
@end lisp

Saving to two groups, @samp{MisK} and @samp{safe}:
@lisp
(setq gnus-message-archive-group '("MisK" "safe"))
@end lisp

Save to different groups based on what group you are in:
@lisp
(setq gnus-message-archive-group
      '(("^alt" "sent-to-alt")
        ("mail" "sent-to-mail")
        (".*" "sent-to-misc")))
@end lisp

More complex stuff:
@lisp
(setq gnus-message-archive-group
      '((if (message-news-p)
            "misc-news"
          "misc-mail")))
@end lisp

How about storing all news messages in one file, but storing all mail
messages in one file per month:

@lisp
(setq gnus-message-archive-group
      '((if (message-news-p)
            "misc-news"
          (concat "mail." (format-time-string "%Y-%m")))))
@end lisp

Now, when you send a message off, it will be stored in the appropriate
group.  (If you want to disable storing for just one particular message,
you can just remove the @code{Gcc} header that has been inserted.)  The
archive group will appear in the group buffer the next time you start
Gnus, or the next time you press @kbd{F} in the group buffer.  You can
enter it and read the articles in it just like you'd read any other
group.  If the group gets really big and annoying, you can simply rename
if (using @kbd{G r} in the group buffer) to something
nice---@samp{misc-mail-september-1995}, or whatever.  New messages will
continue to be stored in the old (now empty) group.

@table @code
@item gnus-gcc-mark-as-read
@vindex gnus-gcc-mark-as-read
If non-@code{nil}, automatically mark @code{Gcc} articles as read.

@item gnus-gcc-externalize-attachments
@vindex gnus-gcc-externalize-attachments
If @code{nil}, attach files as normal parts in Gcc copies; if a regexp
and matches the Gcc group name, attach files as external parts; if it is
@code{all}, attach local files as external parts; if it is other
non-@code{nil}, the behavior is the same as @code{all}, but it may be
changed in the future.

@item gnus-gcc-self-resent-messages
@vindex gnus-gcc-self-resent-messages
Like the @code{gcc-self} group parameter, applied only for unmodified
messages that @code{gnus-summary-resend-message} (@pxref{Summary Mail
Commands}) resends.  Non-@code{nil} value of this variable takes
precedence over any existing @code{Gcc} header.

If this is @code{none}, no @code{Gcc} copy will be made.  If this is
@code{t}, messages resent will be @code{Gcc} copied to the current
group.  If this is a string, it specifies a group to which resent
messages will be @code{Gcc} copied.  If this is @code{nil}, @code{Gcc}
will be done according to existing @code{Gcc} header(s), if any.  If
this is @code{no-gcc-self}, that is the default, resent messages will be
@code{Gcc} copied to groups that existing @code{Gcc} header specifies,
except for the current group.

@item gnus-gcc-pre-body-encode-hook
@vindex gnus-gcc-pre-body-encode-hook
@itemx gnus-gcc-post-body-encode-hook
@vindex gnus-gcc-post-body-encode-hook

These hooks are run before/after encoding the message body of the Gcc
copy of a sent message.  The current buffer (when the hook is run)
contains the message including the message header.  Changes made to
the message will only affect the Gcc copy, but not the original
message.  You can use these hooks to edit the copy (and influence
subsequent transformations), e.g., remove MML secure tags
(@pxref{Signing and encrypting}).

@end table


@node Posting Styles
@section Posting Styles
@cindex posting styles
@cindex styles

All them variables, they make my head swim.

So what if you want a different @code{Organization} and signature based
on what groups you post to?  And you post both from your home machine
and your work machine, and you want different @code{From} lines, and so
on?

@vindex gnus-posting-styles
One way to do stuff like that is to write clever hooks that change the
variables you need to have changed.  That's a bit boring, so somebody
came up with the bright idea of letting the user specify these things in
a handy alist.  Here's an example of a @code{gnus-posting-styles}
variable:

@lisp
((".*"
  (signature "Peace and happiness")
  (organization "What me?"))
 ("^comp"
  (signature "Death to everybody"))
 ("comp.emacs.i-love-it"
  (organization "Emacs is it")))
@end lisp

As you might surmise from this example, this alist consists of several
@dfn{styles}.  Each style will be applicable if the first element
``matches'', in some form or other.  The entire alist will be iterated
over, from the beginning towards the end, and each match will be
applied, which means that attributes in later styles that match override
the same attributes in earlier matching styles.  So
@samp{comp.programming.literate} will have the @samp{Death to everybody}
signature and the @samp{What me?} @code{Organization} header.

The first element in each style is called the @code{match}.  If it's a
string, then Gnus will try to regexp match it against the group name.
If it is the form @code{(header @var{match} @var{regexp})}, then Gnus
will look in the original article for a header whose name is
@var{match} and compare that @var{regexp}.  @var{match} and
@var{regexp} are strings.  (The original article is the one you are
replying or following up to.  If you are not composing a reply or a
followup, then there is nothing to match against.)  If the
@code{match} is a function symbol, that function will be called with
no arguments.  If it's a variable symbol, then the variable will be
referenced.  If it's a list, then that list will be @code{eval}ed.  In
any case, if this returns a non-@code{nil} value, then the style is
said to @dfn{match}.

Each style may contain an arbitrary amount of @dfn{attributes}.  Each
attribute consists of a @code{(@var{name} @var{value})} pair.  In
addition, you can also use the @code{(@var{name} :file @var{value})}
form or the @code{(@var{name} :value @var{value})} form.  Where
@code{:file} signifies @var{value} represents a file name and its
contents should be used as the attribute value, @code{:value} signifies
@var{value} does not represent a file name explicitly.  The attribute
name can be one of:

@itemize @bullet
@item @code{signature}
@item @code{signature-file}
@item @code{x-face-file}
@item @code{address}, overriding @code{user-mail-address}
@item @code{name}, overriding @code{(user-full-name)}
@item @code{body}
@end itemize

Note that the @code{signature-file} attribute honors the variable
@code{message-signature-directory}.

The attribute name can also be a string or a symbol.  In that case,
this will be used as a header name, and the value will be inserted in
the headers of the article; if the value is @code{nil}, the header
name will be removed.  If the attribute name is @code{eval}, the form
is evaluated, and the result is thrown away.

The attribute value can be a string, a function with zero arguments
(the return value will be used), a variable (its value will be used)
or a list (it will be @code{eval}ed and the return value will be
used).  The functions and sexps are called/@code{eval}ed in the
message buffer that is being set up.  The headers of the current
article are available through the @code{message-reply-headers}
variable, which is a vector of the following headers: number subject
from date id references chars lines xref extra.

In the case of a string value, if the @code{match} is a regular
expression, a @samp{gnus-match-substitute-replacement} is proceed on
the value to replace the positional parameters @samp{\@var{n}} by the
corresponding parenthetical matches (see @xref{Replacing Match,,
Replacing the Text that Matched, elisp, The Emacs Lisp Reference Manual}.)

@vindex message-reply-headers

If you wish to check whether the message you are about to compose is
meant to be a news article or a mail message, you can check the values
of the @code{message-news-p} and @code{message-mail-p} functions.

@findex message-mail-p
@findex message-news-p

So here's a new example:

@lisp
(setq gnus-posting-styles
      '((".*"
         (signature-file "~/.signature")
         (name "User Name")
         (x-face-file "~/.xface")
         (x-url (getenv "WWW_HOME"))
         (organization "People's Front Against MWM"))
        ("^rec.humor"
         (signature my-funny-signature-randomizer))
        ((equal (system-name) "gnarly")  ;; @r{A form}
         (signature my-quote-randomizer))
        (message-news-p        ;; @r{A function symbol}
         (signature my-news-signature))
        (window-system         ;; @r{A value symbol}
         ("X-Window-System" (format "%s" window-system)))
        ;; @r{If I'm replying to Larsi, set the Organization header.}
        ((header "from" "larsi.*org")
         (Organization "Somewhere, Inc."))
        ((posting-from-work-p) ;; @r{A user defined function}
         (signature-file "~/.work-signature")
         (address "user@@bar.foo")
         (body "You are fired.\n\nSincerely, your boss.")
         ("X-Message-SMTP-Method" "smtp smtp.example.org 587")
         (organization "Important Work, Inc"))
        ("nnml:.*"
         (From (with-current-buffer gnus-article-buffer
                 (message-fetch-field "to"))))
        ("^nn.+:"
         (signature-file "~/.mail-signature"))))
@end lisp

The @samp{nnml:.*} rule means that you use the @code{To} address as the
@code{From} address in all your outgoing replies, which might be handy
if you fill many roles.
You may also use @code{message-alternative-emails} instead.
@xref{Message Headers, ,Message Headers, message, Message Manual}.

Of particular interest in the ``work-mail'' style is the
@samp{X-Message-SMTP-Method} header.  It specifies how to send the
outgoing email.  You may want to sent certain emails through certain
@acronym{SMTP} servers due to company policies, for instance.
@xref{Mail Variables, ,Message Variables, message, Message Manual}.


@node Drafts
@section Drafts
@cindex drafts

If you are writing a message (mail or news) and suddenly remember that
you have a steak in the oven (or some pesto in the food processor, you
craaazy vegetarians), you'll probably wish there was a method to save
the message you are writing so that you can continue editing it some
other day, and send it when you feel its finished.

Well, don't worry about it.  Whenever you start composing a message of
some sort using the Gnus mail and post commands, the buffer you get will
automatically associate to an article in a special @dfn{draft} group.
If you save the buffer the normal way (@kbd{C-x C-s}, for instance), the
article will be saved there.  (Auto-save files also go to the draft
group.)

@cindex nndraft
@vindex nndraft-directory
The draft group is a special group (which is implemented as an
@code{nndraft} group, if you absolutely have to know) called
@samp{nndraft:drafts}.  The variable @code{nndraft-directory} says where
@code{nndraft} is to store its files.  What makes this group special is
that you can't tick any articles in it or mark any articles as
read---all articles in the group are permanently unread.

If the group doesn't exist, it will be created and you'll be subscribed
to it.  The only way to make it disappear from the Group buffer is to
unsubscribe it.  The special properties of the draft group comes from
a group property (@pxref{Group Parameters}), and if lost the group
behaves like any other group.  This means the commands below will not
be available.  To restore the special properties of the group, the
simplest way is to kill the group, using @kbd{C-k}, and restart
Gnus.  The group is automatically created again with the
correct parameters.  The content of the group is not lost.

@c @findex gnus-dissociate-buffer-from-draft
@c @kindex C-c M-d (Mail)
@c @kindex C-c M-d (Post)
@c @findex gnus-associate-buffer-with-draft
@c @kindex C-c C-d (Mail)
@c @kindex C-c C-d (Post)
@c If you're writing some super-secret message that you later want to
@c encode with PGP before sending, you may wish to turn the auto-saving
@c (and association with the draft group) off.  You never know who might be
@c interested in reading all your extremely valuable and terribly horrible
@c and interesting secrets.  The @kbd{C-c M-d}
@c (@code{gnus-dissociate-buffer-from-draft}) command does that for you.
@c If you change your mind and want to turn the auto-saving back on again,
@c @kbd{C-c C-d} (@code{gnus-associate-buffer-with-draft} does that.
@c
@c @vindex gnus-use-draft
@c To leave association with the draft group off by default, set
@c @code{gnus-use-draft} to @code{nil}.  It is @code{t} by default.

@findex gnus-draft-edit-message
@kindex D e (Draft)
When you want to continue editing the article, you simply enter the
draft group and push @kbd{D e} (@code{gnus-draft-edit-message}) to do
that.  You will be placed in a buffer where you left off.

Rejected articles will also be put in this draft group (@pxref{Rejected
Articles}).

@findex gnus-draft-send-all-messages
@kindex D s (Draft)
@findex gnus-draft-send-message
@kindex D S (Draft)
If you have lots of rejected messages you want to post (or mail) without
doing further editing, you can use the @kbd{D s} command
(@code{gnus-draft-send-message}).  This command understands the
process/prefix convention (@pxref{Process/Prefix}).  The @kbd{D S}
command (@code{gnus-draft-send-all-messages}) will ship off all messages
in the buffer.

@findex gnus-draft-toggle-sending
@kindex D t (Draft)
If you have some messages that you wish not to send, you can use the
@kbd{D t} (@code{gnus-draft-toggle-sending}) command to mark the message
as unsendable.  This is a toggling command.

Finally, if you want to delete a draft, use the normal @kbd{B DEL}
command (@pxref{Mail Group Commands}).


@node Rejected Articles
@section Rejected Articles
@cindex rejected articles

Sometimes a news server will reject an article.  Perhaps the server
doesn't like your face.  Perhaps it just feels miserable.  Perhaps
@emph{there be demons}.  Perhaps you have included too much cited text.
Perhaps the disk is full.  Perhaps the server is down.

These situations are, of course, totally beyond the control of Gnus.
(Gnus, of course, loves the way you look, always feels great, has angels
fluttering around inside of it, doesn't care about how much cited text
you include, never runs full and never goes down.)  So Gnus saves these
articles until some later time when the server feels better.

The rejected articles will automatically be put in a special draft group
(@pxref{Drafts}).  When the server comes back up again, you'd then
typically enter that group and send all the articles off.

@node Signing and encrypting
@section Signing and encrypting
@cindex using gpg
@cindex using s/mime
@cindex using smime

Gnus can digitally sign and encrypt your messages, using vanilla
@acronym{PGP} format or @acronym{PGP/MIME} or @acronym{S/MIME}.  For
decoding such messages, see the @code{mm-verify-option} and
@code{mm-decrypt-option} options (@pxref{Security}).

@vindex gnus-message-replysign
@vindex gnus-message-replyencrypt
@vindex gnus-message-replysignencrypted
Often, you would like to sign replies to people who send you signed
messages.  Even more often, you might want to encrypt messages which
are in reply to encrypted messages.  Gnus offers
@code{gnus-message-replysign} to enable the former, and
@code{gnus-message-replyencrypt} for the latter.  In addition, setting
@code{gnus-message-replysignencrypted} (on by default) will sign
automatically encrypted messages.

Instructing @acronym{MML} to perform security operations on a
@acronym{MIME} part is done using the @kbd{C-c C-m s} key map for
signing and the @kbd{C-c C-m c} key map for encryption, as follows.

@table @kbd

@item C-c C-m s s
@kindex C-c C-m s s (Message)
@findex mml-secure-message-sign-smime

Digitally sign current message using @acronym{S/MIME}.

@item C-c C-m s o
@kindex C-c C-m s o (Message)
@findex mml-secure-message-sign-pgp

Digitally sign current message using @acronym{PGP}.

@item C-c C-m s p
@kindex C-c C-m s p (Message)
@findex mml-secure-message-sign-pgp

Digitally sign current message using @acronym{PGP/MIME}.

@item C-c C-m c s
@kindex C-c C-m c s (Message)
@findex mml-secure-message-encrypt-smime

Digitally encrypt current message using @acronym{S/MIME}.

@item C-c C-m c o
@kindex C-c C-m c o (Message)
@findex mml-secure-message-encrypt-pgp

Digitally encrypt current message using @acronym{PGP}.

@item C-c C-m c p
@kindex C-c C-m c p (Message)
@findex mml-secure-message-encrypt-pgpmime

Digitally encrypt current message using @acronym{PGP/MIME}.

@item C-c C-m C-n
@kindex C-c C-m C-n (Message)
@findex mml-unsecure-message
Remove security related @acronym{MML} tags from message.

@end table

@xref{Security, ,Security, message, Message Manual}, for more information.

@node Select Methods
@chapter Select Methods
@cindex foreign groups
@cindex select methods

A @dfn{foreign group} is a group not read by the usual (or
default) means.  It could be, for instance, a group from a different
@acronym{NNTP} server, it could be a virtual group, or it could be your own
personal mail group.

A foreign group (or any group, really) is specified by a @dfn{name} and
a @dfn{select method}.  To take the latter first, a select method is a
list where the first element says what back end to use (e.g., @code{nntp},
@code{nnspool}, @code{nnml}) and the second element is the @dfn{server
name}.  There may be additional elements in the select method, where the
value may have special meaning for the back end in question.

One could say that a select method defines a @dfn{virtual server}---so
we do just that (@pxref{Server Buffer}).

The @dfn{name} of the group is the name the back end will recognize the
group as.

For instance, the group @samp{soc.motss} on the @acronym{NNTP} server
@samp{some.where.edu} will have the name @samp{soc.motss} and select
method @code{(nntp "some.where.edu")}.  Gnus will call this group
@samp{nntp+some.where.edu:soc.motss}, even though the @code{nntp}
back end just knows this group as @samp{soc.motss}.

The different methods all have their peculiarities, of course.

@menu
* Server Buffer::               Making and editing virtual servers.
* Getting News::                Reading USENET news with Gnus.
* Using IMAP::                  Reading mail from @acronym{IMAP}.
* Getting Mail::                Reading your personal mail with Gnus.
* Browsing the Web::            Getting messages from a plethora of Web sources.
* Other Sources::               Reading directories, files.
* Combined Groups::             Combining groups into one group.
* Email Based Diary::           Using mails to manage diary events in Gnus.
* Gnus Unplugged::              Reading news and mail offline.
@end menu


@node Server Buffer
@section Server Buffer

Traditionally, a @dfn{server} is a machine or a piece of software that
one connects to, and then requests information from.  Gnus does not
connect directly to any real servers, but does all transactions through
one back end or other.  But that's just putting one layer more between
the actual media and Gnus, so we might just as well say that each
back end represents a virtual server.

For instance, the @code{nntp} back end may be used to connect to several
different actual @acronym{NNTP} servers, or, perhaps, to many different ports
on the same actual @acronym{NNTP} server.  You tell Gnus which back end to
use, and what parameters to set by specifying a @dfn{select method}.

These select method specifications can sometimes become quite
complicated---say, for instance, that you want to read from the
@acronym{NNTP} server @samp{news.funet.fi} on port number 13, which
hangs if queried for @acronym{NOV} headers and has a buggy select.  Ahem.
Anyway, if you had to specify that for each group that used this
server, that would be too much work, so Gnus offers a way of naming
select methods, which is what you do in the server buffer.

To enter the server buffer, use the @kbd{^}
(@code{gnus-group-enter-server-mode}) command in the group buffer.

@menu
* Server Buffer Format::        You can customize the look of this buffer.
* Server Commands::             Commands to manipulate servers.
* Example Methods::             Examples server specifications.
* Creating a Virtual Server::   An example session.
* Server Variables::            Which variables to set.
* Servers and Methods::         You can use server names as select methods.
* Unavailable Servers::         Some servers you try to contact may be down.
@end menu

@vindex gnus-server-mode-hook
@code{gnus-server-mode-hook} is run when creating the server buffer.


@node Server Buffer Format
@subsection Server Buffer Format
@cindex server buffer format

@vindex gnus-server-line-format
You can change the look of the server buffer lines by changing the
@code{gnus-server-line-format} variable.  This is a @code{format}-like
variable, with some simple extensions:

@table @samp

@item h
How the news is fetched---the back end name.

@item n
The name of this server.

@item w
Where the news is to be fetched from---the address.

@item s
The opened/closed/denied status of the server.

@item a
Whether this server is agentized.
@end table

@vindex gnus-server-mode-line-format
The mode line can also be customized by using the
@code{gnus-server-mode-line-format} variable (@pxref{Mode Line
Formatting}).  The following specs are understood:

@table @samp
@item S
Server name.

@item M
Server method.
@end table

Also @pxref{Formatting Variables}.


@node Server Commands
@subsection Server Commands
@cindex server commands

@table @kbd

@item v
@kindex v (Server)
@cindex keys, reserved for users (Server)
The key @kbd{v} is reserved for users.  You can bind it to some
command or better use it as a prefix key.

@item a
@kindex a (Server)
@findex gnus-server-add-server
Add a new server (@code{gnus-server-add-server}).

@item e
@kindex e (Server)
@findex gnus-server-edit-server
Edit a server (@code{gnus-server-edit-server}).

@item S
@kindex S (Server)
@findex gnus-server-show-server
Show the definition of a server (@code{gnus-server-show-server}).

@item SPACE
@kindex SPACE (Server)
@findex gnus-server-read-server
Browse the current server (@code{gnus-server-read-server}).

@item q
@kindex q (Server)
@findex gnus-server-exit
Return to the group buffer (@code{gnus-server-exit}).

@item k
@kindex k (Server)
@findex gnus-server-kill-server
Kill the current server (@code{gnus-server-kill-server}).

@item y
@kindex y (Server)
@findex gnus-server-yank-server
Yank the previously killed server (@code{gnus-server-yank-server}).

@item c
@kindex c (Server)
@findex gnus-server-copy-server
Copy the current server (@code{gnus-server-copy-server}).

@item l
@kindex l (Server)
@findex gnus-server-list-servers
List all servers (@code{gnus-server-list-servers}).

@item s
@kindex s (Server)
@findex gnus-server-scan-server
Request that the server scan its sources for new articles
(@code{gnus-server-scan-server}).  This is mainly sensible with mail
servers.

@item g
@kindex g (Server)
@findex gnus-server-regenerate-server
Request that the server regenerate all its data structures
(@code{gnus-server-regenerate-server}).  This can be useful if you have
a mail back end that has gotten out of sync.

@item z
@kindex z (Server)
@findex gnus-server-compact-server

Compact all groups in the server under point
(@code{gnus-server-compact-server}).  Currently implemented only in
nnml (@pxref{Mail Spool}).  This removes gaps between article numbers,
hence getting a correct total article count.

@end table

Some more commands for closing, disabling, and re-opening servers are
listed in @ref{Unavailable Servers}.


@node Example Methods
@subsection Example Methods

Most select methods are pretty simple and self-explanatory:

@lisp
(nntp "news.funet.fi")
@end lisp

Reading directly from the spool is even simpler:

@lisp
(nnspool "")
@end lisp

As you can see, the first element in a select method is the name of the
back end, and the second is the @dfn{address}, or @dfn{name}, if you
will.

After these two elements, there may be an arbitrary number of
@code{(@var{variable} @var{form})} pairs.

To go back to the first example---imagine that you want to read from
port 15 on that machine.  This is what the select method should
look like then:

@lisp
(nntp "news.funet.fi" (nntp-port-number 15))
@end lisp

You should read the documentation to each back end to find out what
variables are relevant, but here's an @code{nnmh} example:

@code{nnmh} is a mail back end that reads a spool-like structure.  Say
you have two structures that you wish to access: One is your private
mail spool, and the other is a public one.  Here's the possible spec for
your private mail:

@lisp
(nnmh "private" (nnmh-directory "~/private/mail/"))
@end lisp

(This server is then called @samp{private}, but you may have guessed
that.)

Here's the method for a public spool:

@lisp
(nnmh "public"
      (nnmh-directory "/usr/information/spool/")
      (nnmh-get-new-mail nil))
@end lisp

@cindex proxy
@cindex firewall

If you are behind a firewall and only have access to the @acronym{NNTP}
server from the firewall machine, you can instruct Gnus to @code{rlogin}
on the firewall machine and connect with
@uref{http://netcat.sourceforge.net/, netcat} from there to the
@acronym{NNTP} server.
Doing this can be rather fiddly, but your virtual server definition
should probably look something like this:

@lisp
(nntp "firewall"
      (nntp-open-connection-function nntp-open-via-rlogin-and-netcat)
      (nntp-via-address "the.firewall.machine")
      (nntp-address "the.real.nntp.host"))
@end lisp

If you want to use the wonderful @code{ssh} program to provide a
compressed connection over the modem line, you could add the following
configuration to the example above:

@lisp
      (nntp-via-rlogin-command "ssh")
@end lisp

See also @code{nntp-via-rlogin-command-switches}.  Here's an example for
an indirect connection:

@lisp
(setq gnus-select-method
      '(nntp "indirect"
             (nntp-address "news.server.example")
             (nntp-via-user-name "intermediate_user_name")
             (nntp-via-address "intermediate.host.example")
             (nntp-via-rlogin-command "ssh")
             (nntp-via-rlogin-command-switches ("-C"))
             (nntp-open-connection-function nntp-open-via-rlogin-and-netcat)))
@end lisp

This means that you have to have set up @code{ssh-agent} correctly to
provide automatic authorization, of course.

If you're behind a firewall, but have direct access to the outside world
through a wrapper command like "runsocks", you could open a socksified
netcat connection to the news server as follows:

@lisp
(nntp "outside"
      (nntp-pre-command "runsocks")
      (nntp-open-connection-function nntp-open-netcat-stream)
      (nntp-address "the.news.server"))
@end lisp


@node Creating a Virtual Server
@subsection Creating a Virtual Server

If you're saving lots of articles in the cache by using persistent
articles, you may want to create a virtual server to read the cache.

First you need to add a new server.  The @kbd{a} command does that.  It
would probably be best to use @code{nnml} to read the cache.  You
could also use @code{nnspool} or @code{nnmh}, though.

Type @kbd{a nnml RET cache RET}.

You should now have a brand new @code{nnml} virtual server called
@samp{cache}.  You now need to edit it to have the right definitions.
Type @kbd{e} to edit the server.  You'll be entered into a buffer that
will contain the following:

@lisp
(nnml "cache")
@end lisp

Change that to:

@lisp
(nnml "cache"
         (nnml-directory "~/News/cache/")
         (nnml-active-file "~/News/cache/active"))
@end lisp

Type @kbd{C-c C-c} to return to the server buffer.  If you now press
@kbd{RET} over this virtual server, you should be entered into a browse
buffer, and you should be able to enter any of the groups displayed.


@node Server Variables
@subsection Server Variables
@cindex server variables
@cindex server parameters

One sticky point when defining variables (both on back ends and in Emacs
in general) is that some variables are typically initialized from other
variables when the definition of the variables is being loaded.  If you
change the ``base'' variable after the variables have been loaded, you
won't change the ``derived'' variables.

This typically affects directory and file variables.  For instance,
@code{nnml-directory} is @file{~/Mail/} by default, and all @code{nnml}
directory variables are initialized from that variable, so
@code{nnml-active-file} will be @file{~/Mail/active}.  If you define a
new virtual @code{nnml} server, it will @emph{not} suffice to set just
@code{nnml-directory}---you have to explicitly set all the file
variables to be what you want them to be.  For a complete list of
variables for each back end, see each back end's section later in this
manual, but here's an example @code{nnml} definition:

@lisp
(nnml "public"
      (nnml-directory "~/my-mail/")
      (nnml-active-file "~/my-mail/active")
      (nnml-newsgroups-file "~/my-mail/newsgroups"))
@end lisp

Server variables are often called @dfn{server parameters}.

@node Servers and Methods
@subsection Servers and Methods

Wherever you would normally use a select method
(e.g., @code{gnus-secondary-select-method}, in the group select method,
when browsing a foreign server) you can use a virtual server name
instead.  This could potentially save lots of typing.  And it's nice all
over.


@node Unavailable Servers
@subsection Unavailable Servers

If a server seems to be unreachable, Gnus will mark that server as
@code{denied}.  That means that any subsequent attempt to make contact
with that server will just be ignored.  ``It can't be opened,'' Gnus
will tell you, without making the least effort to see whether that is
actually the case or not.

That might seem quite naughty, but it does make sense most of the time.
Let's say you have 10 groups subscribed to on server
@samp{nephelococcygia.com}.  This server is located somewhere quite far
away from you and the machine is quite slow, so it takes 1 minute just
to find out that it refuses connection to you today.  If Gnus were to
attempt to do that 10 times, you'd be quite annoyed, so Gnus won't
attempt to do that.  Once it has gotten a single ``connection refused'',
it will regard that server as ``down''.

So, what happens if the machine was only feeling unwell temporarily?
How do you test to see whether the machine has come up again?

You jump to the server buffer (@pxref{Server Buffer}) and poke it
with the following commands:

@table @kbd

@item O
@kindex O (Server)
@findex gnus-server-open-server
Try to establish connection to the server on the current line
(@code{gnus-server-open-server}).

@item C
@kindex C (Server)
@findex gnus-server-close-server
Close the connection (if any) to the server
(@code{gnus-server-close-server}).

@item D
@kindex D (Server)
@findex gnus-server-deny-server
Mark the current server as unreachable
(@code{gnus-server-deny-server}).

@item M-o
@kindex M-o (Server)
@findex gnus-server-open-all-servers
Open the connections to all servers in the buffer
(@code{gnus-server-open-all-servers}).

@item M-c
@kindex M-c (Server)
@findex gnus-server-close-all-servers
Close the connections to all servers in the buffer
(@code{gnus-server-close-all-servers}).

@item R
@kindex R (Server)
@findex gnus-server-remove-denials
Remove all marks to whether Gnus was denied connection from any servers
(@code{gnus-server-remove-denials}).

@item c
@kindex c (Server)
@findex gnus-server-copy-server
Copy a server and give it a new name
(@code{gnus-server-copy-server}).  This can be useful if you have a
complex method definition, and want to use the same definition towards
a different (physical) server.

@item L
@kindex L (Server)
@findex gnus-server-offline-server
Set server status to offline (@code{gnus-server-offline-server}).

@end table


@node Getting News
@section Getting News
@cindex reading news
@cindex news back ends

A newsreader is normally used for reading news.  Gnus currently provides
only two methods of getting news---it can read from an @acronym{NNTP} server,
or it can read from a local spool.

@menu
* NNTP::                        Reading news from an @acronym{NNTP} server.
* News Spool::                  Reading news from the local spool.
@end menu


@node NNTP
@subsection NNTP
@cindex nntp

Subscribing to a foreign group from an @acronym{NNTP} server is rather easy.
You just specify @code{nntp} as method and the address of the @acronym{NNTP}
server as the, uhm, address.

If the @acronym{NNTP} server is located at a non-standard port, setting the
third element of the select method to this port number should allow you
to connect to the right port.  You'll have to edit the group info for
that (@pxref{Foreign Groups}).

The name of the foreign group can be the same as a native group.  In
fact, you can subscribe to the same group from as many different servers
you feel like.  There will be no name collisions.

The following variables can be used to create a virtual @code{nntp}
server:

@table @code

@item nntp-server-opened-hook
@vindex nntp-server-opened-hook
@cindex @sc{mode reader}
@cindex authinfo
@cindex authentication
@cindex nntp authentication
@findex nntp-send-authinfo
@findex nntp-send-mode-reader
is run after a connection has been made.  It can be used to send
commands to the @acronym{NNTP} server after it has been contacted.  By
default it sends the command @code{MODE READER} to the server with the
@code{nntp-send-mode-reader} function.  This function should always be
present in this hook.

@item nntp-authinfo-function
@vindex nntp-authinfo-function
@findex nntp-send-authinfo
@vindex nntp-authinfo-file
This function will be used to send @samp{AUTHINFO} to the @acronym{NNTP}
server.  The default function is @code{nntp-send-authinfo}, which looks
through your @file{~/.authinfo} (or whatever you've set the
@code{nntp-authinfo-file} variable to) for applicable entries.  If none
are found, it will prompt you for a login name and a password.  The
format of the @file{~/.authinfo} file is (almost) the same as the
@code{ftp} @file{~/.netrc} file, which is defined in the @code{ftp}
manual page, but here are the salient facts:

@enumerate
@item
The file contains one or more line, each of which define one server.

@item
Each line may contain an arbitrary number of token/value pairs.

The valid tokens include @samp{machine}, @samp{login}, @samp{password},
@samp{default}.  In addition Gnus introduces two new tokens, not present
in the original @file{.netrc}/@code{ftp} syntax, namely @samp{port} and
@samp{force}.  (This is the only way the @file{.authinfo} file format
deviates from the @file{.netrc} file format.)  @samp{port} is used to
indicate what port on the server the credentials apply to and
@samp{force} is explained below.

@end enumerate

Here's an example file:

@example
machine news.uio.no login larsi password geheimnis
machine nntp.ifi.uio.no login larsi force yes
@end example

The token/value pairs may appear in any order; @samp{machine} doesn't
have to be first, for instance.

In this example, both login name and password have been supplied for the
former server, while the latter has only the login name listed, and the
user will be prompted for the password.  The latter also has the
@samp{force} tag, which means that the authinfo will be sent to the
@var{nntp} server upon connection; the default (i.e., when there is not
@samp{force} tag) is to not send authinfo to the @var{nntp} server
until the @var{nntp} server asks for it.

You can also add @samp{default} lines that will apply to all servers
that don't have matching @samp{machine} lines.

@example
default force yes
@end example

This will force sending @samp{AUTHINFO} commands to all servers not
previously mentioned.

Remember to not leave the @file{~/.authinfo} file world-readable.

@item nntp-server-action-alist
@vindex nntp-server-action-alist
This is a list of regexps to match on server types and actions to be
taken when matches are made.  For instance, if you want Gnus to beep
every time you connect to innd, you could say something like:

@lisp
(setq nntp-server-action-alist
      '(("innd" (ding))))
@end lisp

You probably don't want to do that, though.

The default value is

@lisp
'(("nntpd 1\\.5\\.11t"
   (remove-hook 'nntp-server-opened-hook
                'nntp-send-mode-reader)))
@end lisp

This ensures that Gnus doesn't send the @code{MODE READER} command to
nntpd 1.5.11t, since that command chokes that server, I've been told.

@item nntp-maximum-request
@vindex nntp-maximum-request
If the @acronym{NNTP} server doesn't support @acronym{NOV} headers, this back end
will collect headers by sending a series of @code{head} commands.  To
speed things up, the back end sends lots of these commands without
waiting for reply, and then reads all the replies.  This is controlled
by the @code{nntp-maximum-request} variable, and is 400 by default.  If
your network is buggy, you should set this to 1.

@item nntp-connection-timeout
@vindex nntp-connection-timeout
If you have lots of foreign @code{nntp} groups that you connect to
regularly, you're sure to have problems with @acronym{NNTP} servers not
responding properly, or being too loaded to reply within reasonable
time.  This is can lead to awkward problems, which can be helped
somewhat by setting @code{nntp-connection-timeout}.  This is an integer
that says how many seconds the @code{nntp} back end should wait for a
connection before giving up.  If it is @code{nil}, which is the default,
no timeouts are done.

@item nntp-nov-is-evil
@vindex nntp-nov-is-evil
If the @acronym{NNTP} server does not support @acronym{NOV}, you could set this
variable to @code{t}, but @code{nntp} usually checks automatically whether @acronym{NOV}
can be used.

@item nntp-xover-commands
@vindex nntp-xover-commands
@cindex @acronym{NOV}
@cindex XOVER
List of strings used as commands to fetch @acronym{NOV} lines from a
server.  The default value of this variable is @code{("XOVER"
"XOVERVIEW")}.

@item nntp-nov-gap
@vindex nntp-nov-gap
@code{nntp} normally sends just one big request for @acronym{NOV} lines to
the server.  The server responds with one huge list of lines.  However,
if you have read articles 2--5000 in the group, and only want to read
article 1 and 5001, that means that @code{nntp} will fetch 4999 @acronym{NOV}
lines that you will not need.  This variable says how
big a gap between two consecutive articles is allowed to be before the
@code{XOVER} request is split into several request.  Note that if your
network is fast, setting this variable to a really small number means
that fetching will probably be slower.  If this variable is @code{nil},
@code{nntp} will never split requests.  The default is 5.

@item nntp-xref-number-is-evil
@vindex nntp-xref-number-is-evil
When Gnus refers to an article having the @code{Message-ID} that a user
specifies or having the @code{Message-ID} of the parent article of the
current one (@pxref{Finding the Parent}), Gnus sends a @code{HEAD}
command to the @acronym{NNTP} server to know where it is, and the server
returns the data containing the pairs of a group and an article number
in the @code{Xref} header.  Gnus normally uses the article number to
refer to the article if the data shows that that article is in the
current group, while it uses the @code{Message-ID} otherwise.  However,
some news servers, e.g., ones running Diablo, run multiple engines
having the same articles but article numbers are not kept synchronized
between them.  In that case, the article number that appears in the
@code{Xref} header varies by which engine is chosen, so you cannot refer
to the parent article that is in the current group, for instance.  If
you connect to such a server, set this variable to a non-@code{nil}
value, and Gnus never uses article numbers.  For example:

@lisp
(setq gnus-select-method
      '(nntp "newszilla"
             (nntp-address "newszilla.example.com")
             (nntp-xref-number-is-evil t)
             @dots{}))
@end lisp

The default value of this server variable is @code{nil}.

@item nntp-prepare-server-hook
@vindex nntp-prepare-server-hook
A hook run before attempting to connect to an @acronym{NNTP} server.

@item nntp-record-commands
@vindex nntp-record-commands
If non-@code{nil}, @code{nntp} will log all commands it sends to the
@acronym{NNTP} server (along with a timestamp) in the @samp{*nntp-log*}
buffer.  This is useful if you are debugging a Gnus/@acronym{NNTP} connection
that doesn't seem to work.

@item nntp-open-connection-function
@vindex nntp-open-connection-function
It is possible to customize how the connection to the nntp server will
be opened.  If you specify an @code{nntp-open-connection-function}
parameter, Gnus will use that function to establish the connection.
Seven pre-made functions are supplied.  These functions can be grouped
in two categories: direct connection functions (four pre-made), and
indirect ones (three pre-made).

@item nntp-never-echoes-commands
@vindex nntp-never-echoes-commands
Non-@code{nil} means the nntp server never echoes commands.  It is
reported that some nntps server doesn't echo commands.  So, you may want
to set this to non-@code{nil} in the method for such a server setting
@code{nntp-open-connection-function} to @code{nntp-open-ssl-stream} for
example.  The default value is @code{nil}.  Note that the
@code{nntp-open-connection-functions-never-echo-commands} variable
overrides the @code{nil} value of this variable.

@item nntp-open-connection-functions-never-echo-commands
@vindex nntp-open-connection-functions-never-echo-commands
List of functions that never echo commands.  Add or set a function which
you set to @code{nntp-open-connection-function} to this list if it does
not echo commands.  Note that a non-@code{nil} value of the
@code{nntp-never-echoes-commands} variable overrides this variable.  The
default value is @code{(nntp-open-network-stream)}.

@item nntp-prepare-post-hook
@vindex nntp-prepare-post-hook
A hook run just before posting an article.  If there is no
@code{Message-ID} header in the article and the news server provides the
recommended ID, it will be added to the article before running this
hook.  It is useful to make @code{Cancel-Lock} headers even if you
inhibit Gnus to add a @code{Message-ID} header, you could say:

@lisp
(add-hook 'nntp-prepare-post-hook 'canlock-insert-header)
@end lisp

Note that not all servers support the recommended ID@.  This works for
INN versions 2.3.0 and later, for instance.

@item nntp-server-list-active-group
If @code{nil}, then always use @samp{GROUP} instead of @samp{LIST
ACTIVE}.  This is usually slower, but on misconfigured servers that
don't update their active files often, this can help.


@end table

@menu
* Direct Functions::            Connecting directly to the server.
* Indirect Functions::          Connecting indirectly to the server.
* Common Variables::            Understood by several connection functions.
@end menu


@node Direct Functions
@subsubsection Direct Functions
@cindex direct connection functions

These functions are called direct because they open a direct connection
between your machine and the @acronym{NNTP} server.  The behavior of these
functions is also affected by commonly understood variables
(@pxref{Common Variables}).

@table @code
@findex nntp-open-network-stream
@item nntp-open-network-stream
This is the default, and simply connects to some port or other on the
remote system.  If both Emacs and the server supports it, the
connection will be upgraded to an encrypted @acronym{STARTTLS}
connection automatically.

@item network-only
The same as the above, but don't do automatic @acronym{STARTTLS} upgrades.

@findex nntp-open-tls-stream
@item nntp-open-tls-stream
Opens a connection to a server over a @dfn{secure} channel.  To use
this you must have @uref{http://www.gnu.org/software/gnutls/, GnuTLS}
installed.  You then define a server as follows:

@lisp
;; @r{"nntps" is port 563 and is predefined in our @file{/etc/services}}
;; @r{however, @samp{gnutls-cli -p} doesn't like named ports.}
;;
(nntp "snews.bar.com"
      (nntp-open-connection-function nntp-open-tls-stream)
      (nntp-port-number 563)
      (nntp-address "snews.bar.com"))
@end lisp

@findex nntp-open-ssl-stream
@item nntp-open-ssl-stream
Opens a connection to a server over a @dfn{secure} channel.  To use
this you must have @uref{http://www.openssl.org, OpenSSL}
@ignore
@c Defunct URL, ancient package, so don't mention it.
or @uref{ftp://ftp.psy.uq.oz.au/pub/Crypto/SSL, SSLeay}
@end ignore
installed.  You then define a server as follows:

@lisp
;; @r{"snews" is port 563 and is predefined in our @file{/etc/services}}
;; @r{however, @samp{openssl s_client -port} doesn't like named ports.}
;;
(nntp "snews.bar.com"
      (nntp-open-connection-function nntp-open-ssl-stream)
      (nntp-port-number 563)
      (nntp-address "snews.bar.com"))
@end lisp

@findex nntp-open-netcat-stream
@item nntp-open-netcat-stream
Opens a connection to an @acronym{NNTP} server using the @code{netcat}
program.  You might wonder why this function exists, since we have
the default @code{nntp-open-network-stream} which would do the job.  (One
of) the reason(s) is that if you are behind a firewall but have direct
connections to the outside world thanks to a command wrapper like
@code{runsocks}, you can use it like this:

@lisp
(nntp "socksified"
      (nntp-pre-command "runsocks")
      (nntp-open-connection-function nntp-open-netcat-stream)
      (nntp-address "the.news.server"))
@end lisp

With the default method, you would need to wrap your whole Emacs
session, which is not a good idea.

@findex nntp-open-telnet-stream
@item nntp-open-telnet-stream
Like @code{nntp-open-netcat-stream}, but uses @code{telnet} rather than
@code{netcat}.  @code{telnet} is a bit less robust because of things
like line-end-conversion, but sometimes netcat is simply
not available.  The previous example would turn into:

@lisp
(nntp "socksified"
      (nntp-pre-command "runsocks")
      (nntp-open-connection-function nntp-open-telnet-stream)
      (nntp-address "the.news.server")
      (nntp-end-of-line "\n"))
@end lisp
@end table


@node Indirect Functions
@subsubsection Indirect Functions
@cindex indirect connection functions

These functions are called indirect because they connect to an
intermediate host before actually connecting to the @acronym{NNTP} server.
All of these functions and related variables are also said to belong to
the ``via'' family of connection: they're all prefixed with ``via'' to make
things cleaner.  The behavior of these functions is also affected by
commonly understood variables (@pxref{Common Variables}).

@table @code
@item nntp-open-via-rlogin-and-netcat
@findex nntp-open-via-rlogin-and-netcat
Does an @samp{rlogin} on a remote system, and then uses @code{netcat} to connect
to the real @acronym{NNTP} server from there.  This is useful for instance if
you need to connect to a firewall machine first.

@code{nntp-open-via-rlogin-and-netcat}-specific variables:

@table @code
@item nntp-via-rlogin-command
@vindex nntp-via-rlogin-command
Command used to log in on the intermediate host.  The default is
@samp{rsh}, but @samp{ssh} is a popular alternative.

@item nntp-via-rlogin-command-switches
@vindex nntp-via-rlogin-command-switches
List of strings to be used as the switches to
@code{nntp-via-rlogin-command}.  The default is @code{nil}.  If you use
@samp{ssh} for @code{nntp-via-rlogin-command}, you may set this to
@samp{("-C")} in order to compress all data connections.
@end table

@item nntp-open-via-rlogin-and-telnet
@findex nntp-open-via-rlogin-and-telnet
Does essentially the same, but uses @code{telnet} instead of @samp{netcat}
to connect to the real @acronym{NNTP} server from the intermediate host.
@code{telnet} is a bit less robust because of things like
line-end-conversion, but sometimes @code{netcat} is simply not available.

@code{nntp-open-via-rlogin-and-telnet}-specific variables:

@table @code
@item nntp-telnet-command
@vindex nntp-telnet-command
Command used to connect to the real @acronym{NNTP} server from the
intermediate host.  The default is @samp{telnet}.

@item nntp-telnet-switches
@vindex nntp-telnet-switches
List of strings to be used as the switches to the
@code{nntp-telnet-command} command.  The default is @code{("-8")}.

@item nntp-via-rlogin-command
@vindex nntp-via-rlogin-command
Command used to log in on the intermediate host.  The default is
@samp{rsh}, but @samp{ssh} is a popular alternative.

@item nntp-via-rlogin-command-switches
@vindex nntp-via-rlogin-command-switches
List of strings to be used as the switches to
@code{nntp-via-rlogin-command}.  If you use @samp{ssh},  you may need to set
this to @samp{("-t" "-e" "none")} or @samp{("-C" "-t" "-e" "none")} if
the telnet command requires a pseudo-tty allocation on an intermediate
host.  The default is @code{nil}.
@end table

Note that you may want to change the value for @code{nntp-end-of-line}
to @samp{\n} (@pxref{Common Variables}).

@item nntp-open-via-telnet-and-telnet
@findex nntp-open-via-telnet-and-telnet
Does essentially the same, but uses @samp{telnet} instead of
@samp{rlogin} to connect to the intermediate host.

@code{nntp-open-via-telnet-and-telnet}-specific variables:

@table @code
@item nntp-via-telnet-command
@vindex nntp-via-telnet-command
Command used to @code{telnet} the intermediate host.  The default is
@samp{telnet}.

@item nntp-via-telnet-switches
@vindex nntp-via-telnet-switches
List of strings to be used as the switches to the
@code{nntp-via-telnet-command} command.  The default is @samp{("-8")}.

@item nntp-via-user-password
@vindex nntp-via-user-password
Password to use when logging in on the intermediate host.

@item nntp-via-envuser
@vindex nntp-via-envuser
If non-@code{nil}, the intermediate @code{telnet} session (client and
server both) will support the @code{ENVIRON} option and not prompt for
login name.  This works for Solaris @code{telnet}, for instance.

@item nntp-via-shell-prompt
@vindex nntp-via-shell-prompt
Regexp matching the shell prompt on the intermediate host.  The default
is @samp{bash\\|\$ *\r?$\\|> *\r?}.

@end table

Note that you may want to change the value for @code{nntp-end-of-line}
to @samp{\n} (@pxref{Common Variables}).
@end table


Here are some additional variables that are understood by all the above
functions:

@table @code

@item nntp-via-user-name
@vindex nntp-via-user-name
User name to use when connecting to the intermediate host.

@item nntp-via-address
@vindex nntp-via-address
Address of the intermediate host to connect to.

@end table


@node Common Variables
@subsubsection Common Variables

The following variables affect the behavior of all, or several of the
pre-made connection functions.  When not specified, all functions are
affected (the values of the following variables will be used as the
default if each virtual @code{nntp} server doesn't specify those server
variables individually).

@table @code

@item nntp-pre-command
@vindex nntp-pre-command
A command wrapper to use when connecting through a non native
connection function (all except @code{nntp-open-network-stream},
@code{nntp-open-tls-stream}, and @code{nntp-open-ssl-stream}).  This is
where you would put a @samp{SOCKS} wrapper for instance.

@item nntp-address
@vindex nntp-address
The address of the @acronym{NNTP} server.

@item nntp-port-number
@vindex nntp-port-number
Port number to connect to the @acronym{NNTP} server.  The default is
@samp{nntp}.  If you use @acronym{NNTP} over
@acronym{TLS}/@acronym{SSL}, you may want to use integer ports rather
than named ports (i.e., use @samp{563} instead of @samp{snews} or
@samp{nntps}), because external @acronym{TLS}/@acronym{SSL} tools may
not work with named ports.

@item nntp-end-of-line
@vindex nntp-end-of-line
String to use as end-of-line marker when talking to the @acronym{NNTP}
server.  This is @samp{\r\n} by default, but should be @samp{\n} when
using a non native telnet connection function.

@item nntp-netcat-command
@vindex nntp-netcat-command
Command to use when connecting to the @acronym{NNTP} server through
@samp{netcat}.  This is @emph{not} for an intermediate host.  This is
just for the real @acronym{NNTP} server.  The default is
@samp{nc}.

@item nntp-netcat-switches
@vindex nntp-netcat-switches
A list of switches to pass to @code{nntp-netcat-command}.  The default
is @samp{()}.

@end table

@node News Spool
@subsection News Spool
@cindex nnspool
@cindex news spool

Subscribing to a foreign group from the local spool is extremely easy,
and might be useful, for instance, to speed up reading groups that
contain very big articles---@samp{alt.binaries.pictures.furniture}, for
instance.

Anyway, you just specify @code{nnspool} as the method and @code{""} (or
anything else) as the address.

If you have access to a local spool, you should probably use that as the
native select method (@pxref{Finding the News}).  It is normally faster
than using an @code{nntp} select method, but might not be.  It depends.
You just have to try to find out what's best at your site.

@table @code

@item nnspool-inews-program
@vindex nnspool-inews-program
Program used to post an article.

@item nnspool-inews-switches
@vindex nnspool-inews-switches
Parameters given to the inews program when posting an article.

@item nnspool-spool-directory
@vindex nnspool-spool-directory
Where @code{nnspool} looks for the articles.  This is normally
@file{/usr/spool/news/}.

@item nnspool-nov-directory
@vindex nnspool-nov-directory
Where @code{nnspool} will look for @acronym{NOV} files.  This is normally@*
@file{/usr/spool/news/over.view/}.

@item nnspool-lib-dir
@vindex nnspool-lib-dir
Where the news lib dir is (@file{/usr/lib/news/} by default).

@item nnspool-active-file
@vindex nnspool-active-file
The name of the active file.

@item nnspool-newsgroups-file
@vindex nnspool-newsgroups-file
The name of the group descriptions file.

@item nnspool-history-file
@vindex nnspool-history-file
The name of the news history file.

@item nnspool-active-times-file
@vindex nnspool-active-times-file
The name of the active date file.

@item nnspool-nov-is-evil
@vindex nnspool-nov-is-evil
If non-@code{nil}, @code{nnspool} won't try to use any @acronym{NOV} files
that it finds.

@item nnspool-sift-nov-with-sed
@vindex nnspool-sift-nov-with-sed
@cindex sed
If non-@code{nil}, which is the default, use @code{sed} to get the
relevant portion from the overview file.  If @code{nil},
@code{nnspool} will load the entire file into a buffer and process it
there.

@end table


@node Using IMAP
@section Using IMAP
@cindex imap

The most popular mail backend is probably @code{nnimap}, which
provides access to @acronym{IMAP} servers.  @acronym{IMAP} servers
store mail remotely, so the client doesn't store anything locally.
This means that it's a convenient choice when you're reading your mail
from different locations, or with different user agents.

@menu
* Connecting to an IMAP Server::     Getting started with @acronym{IMAP}.
* Customizing the IMAP Connection::  Variables for @acronym{IMAP} connection.
* Client-Side IMAP Splitting::       Put mail in the correct mail box.
@end menu


@node Connecting to an IMAP Server
@subsection Connecting to an IMAP Server

Connecting to an @acronym{IMAP} can be very easy.  Type @kbd{B} in the
group buffer, or (if your primary interest is reading email), say
something like:

@example
(setq gnus-select-method
      '(nnimap "imap.gmail.com"))
@end example

You'll be prompted for a user name and password.  If you grow tired of
that, then add the following to your @file{~/.authinfo} file:

@example
machine imap.gmail.com login <username> password <password> port imap
@end example

That should basically be it for most users.


@node Customizing the IMAP Connection
@subsection Customizing the IMAP Connection

Here's an example method that's more complex:

@example
(nnimap "imap.gmail.com"
        (nnimap-inbox "INBOX")
        (nnimap-split-methods default)
        (nnimap-expunge t)
        (nnimap-stream ssl))
@end example

@table @code
@item nnimap-address
The address of the server, like @samp{imap.gmail.com}.

@item nnimap-server-port
If the server uses a non-standard port, that can be specified here.  A
typical port would be @code{"imap"} or @code{"imaps"}.

@item nnimap-stream
How @code{nnimap} should connect to the server.  Possible values are:

@table @code
@item undecided
This is the default, and this first tries the @code{ssl} setting, and
then tries the @code{network} setting.

@item ssl
This uses standard @acronym{TLS}/@acronym{SSL} connections.

@item network
Non-encrypted and unsafe straight socket connection, but will upgrade
to encrypted @acronym{STARTTLS} if both Emacs and the server
supports it.

@item starttls
Encrypted @acronym{STARTTLS} over the normal @acronym{IMAP} port.

@item shell
If you need to tunnel via other systems to connect to the server, you
can use this option, and customize @code{nnimap-shell-program} to be
what you need.

@end table

@item nnimap-authenticator
Some @acronym{IMAP} servers allow anonymous logins.  In that case,
this should be set to @code{anonymous}.  If this variable isn't set,
the normal login methods will be used.  If you wish to specify a
specific login method to be used, you can set this variable to either
@code{login} (the traditional @acronym{IMAP} login method),
@code{plain} or @code{cram-md5}.

@item nnimap-expunge
If non-@code{nil}, expunge articles after deleting them.  This is always done
if the server supports UID EXPUNGE, but it's not done by default on
servers that doesn't support that command.

@item nnimap-streaming
Virtually all @acronym{IMAP} server support fast streaming of data.
If you have problems connecting to the server, try setting this to
@code{nil}.

@item nnimap-fetch-partial-articles
If non-@code{nil}, fetch partial articles from the server.  If set to
a string, then it's interpreted as a regexp, and parts that have
matching types will be fetched.  For instance, @samp{"text/"} will
fetch all textual parts, while leaving the rest on the server.

@item nnimap-record-commands
If non-@code{nil}, record all @acronym{IMAP} commands in the
@samp{"*imap log*"} buffer.

@end table


@node Client-Side IMAP Splitting
@subsection Client-Side IMAP Splitting

Many people prefer to do the sorting/splitting of mail into their mail
boxes on the @acronym{IMAP} server.  That way they don't have to
download the mail they're not all that interested in.

If you do want to do client-side mail splitting, then the following
variables are relevant:

@table @code
@item nnimap-inbox
This is the @acronym{IMAP} mail box that will be scanned for new
mail.  This can also be a list of mail box names.

@item nnimap-split-methods
Uses the same syntax as @code{nnmail-split-methods} (@pxref{Splitting
Mail}), except the symbol @code{default}, which means that it should
use the value of the @code{nnmail-split-methods} variable.

@item nnimap-split-fancy
Uses the same syntax as @code{nnmail-split-fancy}.

@item nnimap-unsplittable-articles
List of flag symbols to ignore when doing splitting.  That is,
articles that have these flags won't be considered when splitting.
The default is @samp{(%Deleted %Seen)}.

@end table

Here's a complete example @code{nnimap} backend with a client-side
``fancy'' splitting method:

@example
(nnimap "imap.example.com"
        (nnimap-inbox "INBOX")
        (nnimap-split-methods
         (| ("MailScanner-SpamCheck" "spam" "spam.detected")
            (to "foo@@bar.com" "foo")
            "undecided")))
@end example


@node Getting Mail
@section Getting Mail
@cindex reading mail
@cindex mail

Reading mail with a newsreader---isn't that just plain WeIrD@? But of
course.

@menu
* Mail in a Newsreader::        Important introductory notes.
* Getting Started Reading Mail::  A simple cookbook example.
* Splitting Mail::              How to create mail groups.
* Mail Sources::                How to tell Gnus where to get mail from.
* Mail Back End Variables::     Variables for customizing mail handling.
* Fancy Mail Splitting::        Gnus can do hairy splitting of incoming mail.
* Group Mail Splitting::        Use group customize to drive mail splitting.
* Incorporating Old Mail::      What about the old mail you have?
* Expiring Mail::               Getting rid of unwanted mail.
* Washing Mail::                Removing cruft from the mail you get.
* Duplicates::                  Dealing with duplicated mail.
* Not Reading Mail::            Using mail back ends for reading other files.
* Choosing a Mail Back End::    Gnus can read a variety of mail formats.
@end menu


@node Mail in a Newsreader
@subsection Mail in a Newsreader

If you are used to traditional mail readers, but have decided to switch
to reading mail with Gnus, you may find yourself experiencing something
of a culture shock.

Gnus does not behave like traditional mail readers.  If you want to make
it behave that way, you can, but it's an uphill battle.

Gnus, by default, handles all its groups using the same approach.  This
approach is very newsreaderly---you enter a group, see the new/unread
messages, and when you read the messages, they get marked as read, and
you don't see them any more.  (Unless you explicitly ask for them.)

In particular, you do not do anything explicitly to delete messages.

Does this mean that all the messages that have been marked as read are
deleted?  How awful!

But, no, it means that old messages are @dfn{expired} according to some
scheme or other.  For news messages, the expire process is controlled by
the news administrator; for mail, the expire process is controlled by
you.  The expire process for mail is covered in depth in @ref{Expiring
Mail}.

What many Gnus users find, after using it a while for both news and
mail, is that the transport mechanism has very little to do with how
they want to treat a message.

Many people subscribe to several mailing lists.  These are transported
via @acronym{SMTP}, and are therefore mail.  But we might go for weeks without
answering, or even reading these messages very carefully.  We may not
need to save them because if we should need to read one again, they are
archived somewhere else.

Some people have local news groups which have only a handful of readers.
These are transported via @acronym{NNTP}, and are therefore news.  But we may need
to read and answer a large fraction of the messages very carefully in
order to do our work.  And there may not be an archive, so we may need
to save the interesting messages the same way we would personal mail.

The important distinction turns out to be not the transport mechanism,
but other factors such as how interested we are in the subject matter,
or how easy it is to retrieve the message if we need to read it again.

Gnus provides many options for sorting mail into ``groups'' which behave
like newsgroups, and for treating each group (whether mail or news)
differently.

Some users never get comfortable using the Gnus (ahem) paradigm and wish
that Gnus should grow up and be a male, er, mail reader.  It is possible
to whip Gnus into a more mailreaderly being, but, as said before, it's
not easy.  People who prefer proper mail readers should try @sc{vm}
instead, which is an excellent, and proper, mail reader.

I don't mean to scare anybody off, but I want to make it clear that you
may be required to learn a new way of thinking about messages.  After
you've been subjected to The Gnus Way, you will come to love it.  I can
guarantee it.  (At least the guy who sold me the Emacs Subliminal
Brain-Washing Functions that I've put into Gnus did guarantee it.  You
Will Be Assimilated.  You Love Gnus.  You Love The Gnus Mail Way.
You Do.)


@node Getting Started Reading Mail
@subsection Getting Started Reading Mail

It's quite easy to use Gnus to read your new mail.  You just plonk the
mail back end of your choice into @code{gnus-secondary-select-methods},
and things will happen automatically.

For instance, if you want to use @code{nnml} (which is a ``one file per
mail'' back end), you could put the following in your @file{~/.gnus.el} file:

@lisp
(setq gnus-secondary-select-methods '((nnml "")))
@end lisp

Now, the next time you start Gnus, this back end will be queried for new
articles, and it will move all the messages in your spool file to its
directory, which is @file{~/Mail/} by default.  The new group that will
be created (@samp{mail.misc}) will be subscribed, and you can read it
like any other group.

You will probably want to split the mail into several groups, though:

@lisp
(setq nnmail-split-methods
      '(("junk" "^From:.*Lars Ingebrigtsen")
        ("crazy" "^Subject:.*die\\|^Organization:.*flabby")
        ("other" "")))
@end lisp

This will result in three new @code{nnml} mail groups being created:
@samp{nnml:junk}, @samp{nnml:crazy}, and @samp{nnml:other}.  All the
mail that doesn't fit into the first two groups will be placed in the
last group.

This should be sufficient for reading mail with Gnus.  You might want to
give the other sections in this part of the manual a perusal, though.
Especially @pxref{Choosing a Mail Back End} and @pxref{Expiring Mail}.


@node Splitting Mail
@subsection Splitting Mail
@cindex splitting mail
@cindex mail splitting
@cindex mail filtering (splitting)

@vindex nnmail-split-methods
The @code{nnmail-split-methods} variable says how the incoming mail is
to be split into groups.

@lisp
(setq nnmail-split-methods
  '(("mail.junk" "^From:.*Lars Ingebrigtsen")
    ("mail.crazy" "^Subject:.*die\\|^Organization:.*flabby")
    ("mail.other" "")))
@end lisp

This variable is a list of lists, where the first element of each of
these lists is the name of the mail group (they do not have to be called
something beginning with @samp{mail}, by the way), and the second
element is a regular expression used on the header of each mail to
determine if it belongs in this mail group.  The first string may
contain @samp{\\1} forms, like the ones used by @code{replace-match} to
insert sub-expressions from the matched text.  For instance:

@lisp
("list.\\1" "From:.* \\(.*\\)-list@@majordomo.com")
@end lisp

@noindent
In that case, @code{nnmail-split-lowercase-expanded} controls whether
the inserted text should be made lowercase.  @xref{Fancy Mail Splitting}.

The second element can also be a function.  In that case, it will be
called narrowed to the headers with the first element of the rule as the
argument.  It should return a non-@code{nil} value if it thinks that the
mail belongs in that group.

@cindex @samp{bogus} group
The last of these groups should always be a general one, and the regular
expression should @emph{always} be @samp{""} so that it matches any mails
that haven't been matched by any of the other regexps.  (These rules are
processed from the beginning of the alist toward the end.  The first rule
to make a match will ``win'', unless you have crossposting enabled.  In
that case, all matching rules will ``win''.)  If no rule matched, the mail
will end up in the @samp{bogus} group.  When new groups are created by
splitting mail, you may want to run @code{gnus-group-find-new-groups} to
see the new groups.  This also applies to the @samp{bogus} group.

If you like to tinker with this yourself, you can set this variable to a
function of your choice.  This function will be called without any
arguments in a buffer narrowed to the headers of an incoming mail
message.  The function should return a list of group names that it
thinks should carry this mail message.

This variable can also be a fancy split method.  For the syntax,
see @ref{Fancy Mail Splitting}.

Note that the mail back ends are free to maul the poor, innocent,
incoming headers all they want to.  They all add @code{Lines} headers;
some add @code{X-Gnus-Group} headers; most rename the Unix mbox
@code{From<SPACE>} line to something else.

@vindex nnmail-crosspost
The mail back ends all support cross-posting.  If several regexps match,
the mail will be ``cross-posted'' to all those groups.
@code{nnmail-crosspost} says whether to use this mechanism or not.  Note
that no articles are crossposted to the general (@samp{""}) group.

@vindex nnmail-crosspost-link-function
@cindex crosspost
@cindex links
@code{nnmh} and @code{nnml} makes crossposts by creating hard links to
the crossposted articles.  However, not all file systems support hard
links.  If that's the case for you, set
@code{nnmail-crosspost-link-function} to @code{copy-file}.  (This
variable is @code{add-name-to-file} by default.)

@kindex M-x nnmail-split-history
@findex nnmail-split-history
If you wish to see where the previous mail split put the messages, you
can use the @kbd{M-x nnmail-split-history} command.  If you wish to see
where re-spooling messages would put the messages, you can use
@code{gnus-summary-respool-trace} and related commands (@pxref{Mail
Group Commands}).

@vindex nnmail-split-header-length-limit
Header lines longer than the value of
@code{nnmail-split-header-length-limit} are excluded from the split
function.

@vindex nnmail-mail-splitting-decodes
@vindex nnmail-mail-splitting-charset
By default, splitting does not decode headers, so you can not match on
non-@acronym{ASCII} strings.  But it is useful if you want to match
articles based on the raw header data.  To enable it, set the
@code{nnmail-mail-splitting-decodes} variable to a non-@code{nil} value.
In addition, the value of the @code{nnmail-mail-splitting-charset}
variable is used for decoding non-@acronym{MIME} encoded string when
@code{nnmail-mail-splitting-decodes} is non-@code{nil}.  The default
value is @code{nil} which means not to decode non-@acronym{MIME} encoded
string.  A suitable value for you will be @code{undecided} or be the
charset used normally in mails you are interested in.

@vindex nnmail-resplit-incoming
By default, splitting is performed on all incoming messages.  If you
specify a @code{directory} entry for the variable @code{mail-sources}
(@pxref{Mail Source Specifiers}), however, then splitting does
@emph{not} happen by default.  You can set the variable
@code{nnmail-resplit-incoming} to a non-@code{nil} value to make
splitting happen even in this case.  (This variable has no effect on
other kinds of entries.)

Gnus gives you all the opportunity you could possibly want for shooting
yourself in the foot.  Let's say you create a group that will contain
all the mail you get from your boss.  And then you accidentally
unsubscribe from the group.  Gnus will still put all the mail from your
boss in the unsubscribed group, and so, when your boss mails you ``Have
that report ready by Monday or you're fired!'', you'll never see it and,
come Tuesday, you'll still believe that you're gainfully employed while
you really should be out collecting empty bottles to save up for next
month's rent money.


@node Mail Sources
@subsection Mail Sources

Mail can be gotten from many different sources---the mail spool, from
a @acronym{POP} mail server, from a procmail directory, or from a
maildir, for instance.

@menu
* Mail Source Specifiers::      How to specify what a mail source is.
* Mail Source Functions::
* Mail Source Customization::   Some variables that influence things.
* Fetching Mail::               Using the mail source specifiers.
@end menu


@node Mail Source Specifiers
@subsubsection Mail Source Specifiers
@cindex POP
@cindex mail server
@cindex procmail
@cindex mail spool
@cindex mail source

You tell Gnus how to fetch mail by setting @code{mail-sources}
(@pxref{Fetching Mail}) to a @dfn{mail source specifier}.

Here's an example:

@lisp
(pop :server "pop3.mailserver.com" :user "myname")
@end lisp

As can be observed, a mail source specifier is a list where the first
element is a @dfn{mail source type}, followed by an arbitrary number of
@dfn{keywords}.  Keywords that are not explicitly specified are given
default values.

The @code{mail-sources} is global for all mail groups.  You can specify
an additional mail source for a particular group by including the
@code{group} mail specifier in @code{mail-sources}, and setting a
@code{mail-source} group parameter (@pxref{Group Parameters}) specifying
a single mail source.  When this is used, @code{mail-sources} is
typically just @code{(group)}; the @code{mail-source} parameter for a
group might look like this:

@lisp
(mail-source . (file :path "home/user/spools/foo.spool"))
@end lisp

This means that the group's (and only this group's) messages will be
fetched from the spool file @samp{/user/spools/foo.spool}.

The following mail source types are available:

@table @code
@item file
Get mail from a single file; typically from the mail spool.

Keywords:

@table @code
@item :path
The file name.  Defaults to the value of the @env{MAIL}
environment variable or the value of @code{rmail-spool-directory}
(usually something like @file{/usr/mail/spool/user-name}).

@item :prescript
@itemx :postscript
Script run before/after fetching mail.
@end table

An example file mail source:

@lisp
(file :path "/usr/spool/mail/user-name")
@end lisp

Or using the default file name:

@lisp
(file)
@end lisp

If the mail spool file is not located on the local machine, it's best
to use @acronym{POP} or @acronym{IMAP} or the like to fetch the mail.
You can not use ange-ftp file names here---it has no way to lock the
mail spool while moving the mail.

If it's impossible to set up a proper server, you can use ssh instead.

@lisp
(setq mail-sources
      '((file :prescript "ssh host bin/getmail >%t")))
@end lisp

The @samp{getmail} script would look something like the following:

@example
#!/bin/sh
#  getmail - move mail from spool to stdout
#  flu@@iki.fi

MOVEMAIL=/usr/lib/emacs/20.3/i386-redhat-linux/movemail
TMP=$HOME/Mail/tmp
rm -f $TMP; $MOVEMAIL $MAIL $TMP >/dev/null && cat $TMP
@end example

Alter this script to fit the @samp{movemail} and temporary
file you want to use.


@item directory
@vindex nnmail-scan-directory-mail-source-once
Get mail from several files in a directory.  This is typically used
when you have procmail split the incoming mail into several files.
That is, there is a one-to-one correspondence between files in that
directory and groups, so that mail from the file @file{foo.bar.spool}
will be put in the group @code{foo.bar}.  (You can change the suffix
to be used instead of @code{.spool}.)  Setting
@code{nnmail-scan-directory-mail-source-once} to non-@code{nil} forces
Gnus to scan the mail source only once.  This is particularly useful
if you want to scan mail groups at a specified level.

@vindex nnmail-resplit-incoming
There is also the variable @code{nnmail-resplit-incoming}, if you set
that to a non-@code{nil} value, then the normal splitting process is
applied to all the files from the directory, @ref{Splitting Mail}.

Keywords:

@table @code
@item :path
The name of the directory where the files are.  There is no default
value.

@item :suffix
Only files ending with this suffix are used.  The default is
@samp{.spool}.

@item :predicate
Only files that have this predicate return non-@code{nil} are returned.
The default is @code{identity}.  This is used as an additional
filter---only files that have the right suffix @emph{and} satisfy this
predicate are considered.

@item :prescript
@itemx :postscript
Script run before/after fetching mail.

@end table

An example directory mail source:

@lisp
(directory :path "/home/user-name/procmail-dir/"
           :suffix ".prcml")
@end lisp

@item pop
Get mail from a @acronym{POP} server.

Keywords:

@table @code
@item :server
The name of the @acronym{POP} server.  The default is taken from the
@env{MAILHOST} environment variable.

@item :port
The port number of the @acronym{POP} server.  This can be a number (e.g.,
@samp{:port 1234}) or a string (e.g., @samp{:port "pop3"}).  If it is a
string, it should be a service name as listed in @file{/etc/services} on
Unix systems.  The default is @samp{"pop3"}.  On some systems you might
need to specify it as @samp{"pop-3"} instead.

@item :user
The user name to give to the @acronym{POP} server.  The default is the login
name.

@item :password
The password to give to the @acronym{POP} server.  If not specified,
the user is prompted.

@item :program
The program to use to fetch mail from the @acronym{POP} server.  This
should be a @code{format}-like string.  Here's an example:

@example
fetchmail %u@@%s -P %p %t
@end example

The valid format specifier characters are:

@table @samp
@item t
The name of the file the mail is to be moved to.  This must always be
included in this string.

@item s
The name of the server.

@item P
The port number of the server.

@item u
The user name to use.

@item p
The password to use.
@end table

The values used for these specs are taken from the values you give the
corresponding keywords.

@item :prescript
A script to be run before fetching the mail.  The syntax is the same as
the @code{:program} keyword.  This can also be a function to be run.

One popular way to use this is to set up an SSH tunnel to access the
@acronym{POP} server.  Here's an example:

@lisp
(pop :server "127.0.0.1"
     :port 1234
     :user "foo"
     :password "secret"
     :prescript
     "nohup ssh -f -L 1234:pop.server:110 remote.host sleep 3600 &")
@end lisp

@item :postscript
A script to be run after fetching the mail.  The syntax is the same as
the @code{:program} keyword.  This can also be a function to be run.

@item :function
The function to use to fetch mail from the @acronym{POP} server.  The
function is called with one parameter---the name of the file where the
mail should be moved to.

@item :authentication
This can be either the symbol @code{password} or the symbol @code{apop}
and says what authentication scheme to use.  The default is
@code{password}.

@item :leave
Non-@code{nil} if the mail is to be left on the @acronym{POP} server
after fetching.  Mails once fetched will never be fetched again by the
@acronym{UIDL} control.  Only the built-in @code{pop3-movemail} program
(the default) supports this keyword.

If this is neither @code{nil} nor a number, all mails will be left on
the server.  If this is a number, leave mails on the server for this
many days since you first checked new mails.  If this is @code{nil}
(the default), mails will be deleted on the server right after fetching.

@vindex pop3-uidl-file
The @code{pop3-uidl-file} variable specifies the file to which the
@acronym{UIDL} data are locally stored.  The default value is
@file{~/.pop3-uidl}.

Note that @acronym{POP} servers maintain no state information between
sessions, so what the client believes is there and what is actually
there may not match up.  If they do not, then you may get duplicate
mails or the whole thing can fall apart and leave you with a corrupt
mailbox.

@end table

@findex pop3-movemail
@vindex pop3-leave-mail-on-server
If the @code{:program} and @code{:function} keywords aren't specified,
@code{pop3-movemail} will be used.

Here are some examples for getting mail from a @acronym{POP} server.

Fetch from the default @acronym{POP} server, using the default user
name, and default fetcher:

@lisp
(pop)
@end lisp

Fetch from a named server with a named user and password:

@lisp
(pop :server "my.pop.server"
     :user "user-name" :password "secret")
@end lisp

Leave mails on the server for 14 days:

@lisp
(pop :server "my.pop.server"
     :user "user-name" :password "secret"
     :leave 14)
@end lisp

Use @samp{movemail} to move the mail:

@lisp
(pop :program "movemail po:%u %t %p")
@end lisp

@item maildir
Get mail from a maildir.  This is a type of mailbox that is supported by
at least qmail and postfix, where each file in a special directory
contains exactly one mail.

Keywords:

@table @code
@item :path
The name of the directory where the mails are stored.  The default is
taken from the @env{MAILDIR} environment variable or
@file{~/Maildir/}.
@item :subdirs
The subdirectories of the Maildir.  The default is
@samp{("new" "cur")}.

@c If you sometimes look at your mail through a pop3 daemon before fetching
@c them with Gnus, you may also have to fetch your mails from the
@c @code{cur} directory inside the maildir, like in the first example
@c below.

You can also get mails from remote hosts (because maildirs don't suffer
from locking problems).

@end table

Two example maildir mail sources:

@lisp
(maildir :path "/home/user-name/Maildir/"
         :subdirs ("cur" "new"))
@end lisp

@lisp
(maildir :path "/user@@remotehost.org:~/Maildir/"
         :subdirs ("new"))
@end lisp

@item imap
Get mail from a @acronym{IMAP} server.  If you don't want to use
@acronym{IMAP} as intended, as a network mail reading protocol (i.e.,
with nnimap), for some reason or other, Gnus let you treat it similar
to a @acronym{POP} server and fetches articles from a given
@acronym{IMAP} mailbox.  @xref{Using IMAP}, for more information.

Keywords:

@table @code
@item :server
The name of the @acronym{IMAP} server.  The default is taken from the
@env{MAILHOST} environment variable.

@item :port
The port number of the @acronym{IMAP} server.  The default is @samp{143}, or
@samp{993} for @acronym{TLS}/@acronym{SSL} connections.

@item :user
The user name to give to the @acronym{IMAP} server.  The default is the login
name.

@item :password
The password to give to the @acronym{IMAP} server.  If not specified, the user is
prompted.

@item :stream
What stream to use for connecting to the server, this is one of the
symbols in @code{imap-stream-alist}.  Right now, this means
@samp{gssapi}, @samp{kerberos4}, @samp{starttls}, @samp{tls},
@samp{ssl}, @samp{shell} or the default @samp{network}.

@item :authentication
Which authenticator to use for authenticating to the server, this is
one of the symbols in @code{imap-authenticator-alist}.  Right now,
this means @samp{gssapi}, @samp{kerberos4}, @samp{digest-md5},
@samp{cram-md5}, @samp{anonymous} or the default @samp{login}.

@item :program
When using the `shell' :stream, the contents of this variable is
mapped into the @code{imap-shell-program} variable.  This should be a
@code{format}-like string (or list of strings).  Here's an example:

@example
ssh %s imapd
@end example

Make sure nothing is interfering with the output of the program, e.g.,
don't forget to redirect the error output to the void.  The valid format
specifier characters are:

@table @samp
@item s
The name of the server.

@item l
User name from @code{imap-default-user}.

@item p
The port number of the server.
@end table

The values used for these specs are taken from the values you give the
corresponding keywords.

@item :mailbox
The name of the mailbox to get mail from.  The default is @samp{INBOX}
which normally is the mailbox which receives incoming mail.

@item :predicate
The predicate used to find articles to fetch.  The default, @samp{UNSEEN
UNDELETED}, is probably the best choice for most people, but if you
sometimes peek in your mailbox with a @acronym{IMAP} client and mark some
articles as read (or; SEEN) you might want to set this to @samp{1:*}.
Then all articles in the mailbox is fetched, no matter what.  For a
complete list of predicates, see RFC 2060 section 6.4.4.

@item :fetchflag
How to flag fetched articles on the server, the default @samp{\Deleted}
will mark them as deleted, an alternative would be @samp{\Seen} which
would simply mark them as read.  These are the two most likely choices,
but more flags are defined in RFC 2060 section 2.3.2.

@item :dontexpunge
If non-@code{nil}, don't remove all articles marked as deleted in the
mailbox after finishing the fetch.

@end table

An example @acronym{IMAP} mail source:

@lisp
(imap :server "mail.mycorp.com"
      :stream kerberos4
      :fetchflag "\\Seen")
@end lisp

@item group
Get the actual mail source from the @code{mail-source} group parameter,
@xref{Group Parameters}.

@end table

@table @dfn
@item Common Keywords
Common keywords can be used in any type of mail source.

Keywords:

@table @code
@item :plugged
If non-@code{nil}, fetch the mail even when Gnus is unplugged.  If you
use directory source to get mail, you can specify it as in this
example:

@lisp
(setq mail-sources
      '((directory :path "/home/pavel/.Spool/"
                   :suffix ""
                   :plugged t)))
@end lisp

Gnus will then fetch your mail even when you are unplugged.  This is
useful when you use local mail and news.

@end table
@end table

@node Mail Source Functions
@subsubsection Function Interface

Some of the above keywords specify a Lisp function to be executed.
For each keyword @code{:foo}, the Lisp variable @code{foo} is bound to
the value of the keyword while the function is executing.  For example,
consider the following mail-source setting:

@lisp
(setq mail-sources '((pop :user "jrl"
                          :server "pophost" :function fetchfunc)))
@end lisp

While the function @code{fetchfunc} is executing, the symbol @code{user}
is bound to @code{"jrl"}, and the symbol @code{server} is bound to
@code{"pophost"}.  The symbols @code{port}, @code{password},
@code{program}, @code{prescript}, @code{postscript}, @code{function},
and @code{authentication} are also bound (to their default values).

See above for a list of keywords for each type of mail source.


@node Mail Source Customization
@subsubsection Mail Source Customization

The following is a list of variables that influence how the mail is
fetched.  You would normally not need to set or change any of these
variables.

@table @code
@item mail-source-crash-box
@vindex mail-source-crash-box
File where mail will be stored while processing it.  The default is@*
@file{~/.emacs-mail-crash-box}.

@cindex Incoming*
@item mail-source-delete-incoming
@vindex mail-source-delete-incoming
If non-@code{nil}, delete incoming files after handling them.  If
@code{t}, delete the files immediately, if @code{nil}, never delete any
files.  If a positive number, delete files older than number of days
(the deletion will only happen when receiving new mail).  You may also
set @code{mail-source-delete-incoming} to @code{nil} and call
@code{mail-source-delete-old-incoming} from a hook or interactively.
@code{mail-source-delete-incoming} defaults to @code{10} in alpha Gnusae
and @code{2} in released Gnusae.  @xref{Gnus Development}.

@item mail-source-delete-old-incoming-confirm
@vindex mail-source-delete-old-incoming-confirm
If non-@code{nil}, ask for confirmation before deleting old incoming
files.  This variable only applies when
@code{mail-source-delete-incoming} is a positive number.

@item mail-source-ignore-errors
@vindex mail-source-ignore-errors
If non-@code{nil}, ignore errors when reading mail from a mail source.

@item mail-source-directory
@vindex mail-source-directory
Directory where incoming mail source files (if any) will be stored.  The
default is @file{~/Mail/}.  At present, the only thing this is used for
is to say where the incoming files will be stored if the variable
@code{mail-source-delete-incoming} is @code{nil} or a number.

@item mail-source-incoming-file-prefix
@vindex mail-source-incoming-file-prefix
Prefix for file name for storing incoming mail.  The default is
@file{Incoming}, in which case files will end up with names like
@file{Incoming30630D_} or @file{Incoming298602ZD}.  This is really only
relevant if @code{mail-source-delete-incoming} is @code{nil} or a
number.

@item mail-source-default-file-modes
@vindex mail-source-default-file-modes
All new mail files will get this file mode.  The default is @code{#o600}.

@item mail-source-movemail-program
@vindex mail-source-movemail-program
If non-@code{nil}, name of program for fetching new mail.  If
@code{nil}, @code{movemail} in @var{exec-directory}.

@end table


@node Fetching Mail
@subsubsection Fetching Mail

@vindex mail-sources
The way to actually tell Gnus where to get new mail from is to set
@code{mail-sources} to a list of mail source specifiers
(@pxref{Mail Source Specifiers}).

If this variable is @code{nil}, the mail back ends will never attempt to
fetch mail by themselves.

If you want to fetch mail both from your local spool as well as a
@acronym{POP} mail server, you'd say something like:

@lisp
(setq mail-sources
      '((file)
        (pop :server "pop3.mail.server"
             :password "secret")))
@end lisp

Or, if you don't want to use any of the keyword defaults:

@lisp
(setq mail-sources
      '((file :path "/var/spool/mail/user-name")
        (pop :server "pop3.mail.server"
             :user "user-name"
             :port "pop3"
             :password "secret")))
@end lisp


When you use a mail back end, Gnus will slurp all your mail from your
inbox and plonk it down in your home directory.  Gnus doesn't move any
mail if you're not using a mail back end---you have to do a lot of magic
invocations first.  At the time when you have finished drawing the
pentagram, lightened the candles, and sacrificed the goat, you really
shouldn't be too surprised when Gnus moves your mail.



@node Mail Back End Variables
@subsection Mail Back End Variables

These variables are (for the most part) pertinent to all the various
mail back ends.

@table @code
@vindex nnmail-read-incoming-hook
@item nnmail-read-incoming-hook
The mail back ends all call this hook after reading new mail.  You can
use this hook to notify any mail watch programs, if you want to.

@vindex nnmail-split-hook
@item nnmail-split-hook
@findex gnus-article-decode-encoded-words
@cindex RFC 1522 decoding
@cindex RFC 2047 decoding
Hook run in the buffer where the mail headers of each message is kept
just before the splitting based on these headers is done.  The hook is
free to modify the buffer contents in any way it sees fit---the buffer
is discarded after the splitting has been done, and no changes performed
in the buffer will show up in any files.
@code{gnus-article-decode-encoded-words} is one likely function to add
to this hook.

@vindex nnmail-pre-get-new-mail-hook
@vindex nnmail-post-get-new-mail-hook
@item nnmail-pre-get-new-mail-hook
@itemx nnmail-post-get-new-mail-hook
These are two useful hooks executed when treating new incoming
mail---@code{nnmail-pre-get-new-mail-hook} (is called just before
starting to handle the new mail) and
@code{nnmail-post-get-new-mail-hook} (is called when the mail handling
is done).  Here's and example of using these two hooks to change the
default file modes the new mail files get:

@lisp
(add-hook 'nnmail-pre-get-new-mail-hook
          (lambda () (set-default-file-modes #o700)))

(add-hook 'nnmail-post-get-new-mail-hook
          (lambda () (set-default-file-modes #o775)))
@end lisp

@item nnmail-use-long-file-names
@vindex nnmail-use-long-file-names
If non-@code{nil}, the mail back ends will use long file and directory
names.  Groups like @samp{mail.misc} will end up in directories
(assuming use of @code{nnml} back end) or files (assuming use of
@code{nnfolder} back end) like @file{mail.misc}.  If it is @code{nil},
the same group will end up in @file{mail/misc}.

@item nnmail-delete-file-function
@vindex nnmail-delete-file-function
@findex delete-file
Function called to delete files.  It is @code{delete-file} by default.

@item nnmail-cache-accepted-message-ids
@vindex nnmail-cache-accepted-message-ids
If non-@code{nil}, put the @code{Message-ID}s of articles imported into
the back end (via @code{Gcc}, for instance) into the mail duplication
discovery cache.  The default is @code{nil}.

@item nnmail-cache-ignore-groups
@vindex nnmail-cache-ignore-groups
This can be a regular expression or a list of regular expressions.
Group names that match any of the regular expressions will never be
recorded in the @code{Message-ID} cache.

This can be useful, for example, when using Fancy Splitting
(@pxref{Fancy Mail Splitting}) together with the function
@code{nnmail-split-fancy-with-parent}.

@end table


@node Fancy Mail Splitting
@subsection Fancy Mail Splitting
@cindex mail splitting
@cindex fancy mail splitting

@vindex nnmail-split-fancy
@findex nnmail-split-fancy
If the rather simple, standard method for specifying how to split mail
doesn't allow you to do what you want, you can set
@code{nnmail-split-methods} to @code{nnmail-split-fancy}.  Then you can
play with the @code{nnmail-split-fancy} variable.

Let's look at an example value of this variable first:

@lisp
;; @r{Messages from the mailer daemon are not crossposted to any of}
;; @r{the ordinary groups.  Warnings are put in a separate group}
;; @r{from real errors.}
(| ("from" mail (| ("subject" "warn.*" "mail.warning")
                   "mail.misc"))
   ;; @r{Non-error messages are crossposted to all relevant}
   ;; @r{groups, but we don't crosspost between the group for the}
   ;; @r{(ding) list and the group for other (ding) related mail.}
   (& (| (any "ding@@ifi\\.uio\\.no" "ding.list")
         ("subject" "ding" "ding.misc"))
      ;; @r{Other mailing lists@dots{}}
      (any "procmail@@informatik\\.rwth-aachen\\.de" "procmail.list")
      (any "SmartList@@informatik\\.rwth-aachen\\.de" "SmartList.list")
      ;; @r{Both lists below have the same suffix, so prevent}
      ;; @r{cross-posting to mkpkg.list of messages posted only to}
      ;; @r{the bugs- list, but allow cross-posting when the}
      ;; @r{message was really cross-posted.}
      (any "bugs-mypackage@@somewhere" "mypkg.bugs")
      (any "mypackage@@somewhere" - "bugs-mypackage" "mypkg.list")
      ;; @r{People@dots{}}
      (any "larsi@@ifi\\.uio\\.no" "people.Lars_Magne_Ingebrigtsen"))
   ;; @r{Unmatched mail goes to the catch all group.}
   "misc.misc")
@end lisp

This variable has the format of a @dfn{split}.  A split is a
(possibly) recursive structure where each split may contain other
splits.  Here are the possible split syntaxes:

@table @code

@item group
If the split is a string, that will be taken as a group name.  Normal
regexp match expansion will be done.  See below for examples.

@c Don't fold this line.
@item (@var{field} @var{value} [- @var{restrict} [@dots{}] ] @var{split} [@var{invert-partial}])
The split can be a list containing at least three elements.  If the
first element @var{field} (a regexp matching a header) contains
@var{value} (also a regexp) then store the message as specified by
@var{split}.

If @var{restrict} (yet another regexp) matches some string after
@var{field} and before the end of the matched @var{value}, the
@var{split} is ignored.  If none of the @var{restrict} clauses match,
@var{split} is processed.

The last element @var{invert-partial} is optional.  If it is
non-@code{nil}, the match-partial-words behavior controlled by the
variable @code{nnmail-split-fancy-match-partial-words} (see below) is
be inverted.  (New in Gnus 5.10.7)

@item (| @var{split} @dots{})
If the split is a list, and the first element is @code{|} (vertical
bar), then process each @var{split} until one of them matches.  A
@var{split} is said to match if it will cause the mail message to be
stored in one or more groups.

@item (& @var{split} @dots{})
If the split is a list, and the first element is @code{&}, then
process all @var{split}s in the list.

@item junk
If the split is the symbol @code{junk}, then don't save (i.e., delete)
this message.  Use with extreme caution.

@item (: @var{function} @var{arg1} @var{arg2} @dots{})
If the split is a list, and the first element is @samp{:}, then the
second element will be called as a function with @var{args} given as
arguments.  The function should return a @var{split}.

@cindex body split
For instance, the following function could be used to split based on the
body of the messages:

@lisp
(defun split-on-body ()
  (save-excursion
    (save-restriction
      (widen)
      (goto-char (point-min))
      (when (re-search-forward "Some.*string" nil t)
        "string.group"))))
@end lisp

The buffer is narrowed to the header of the message in question when
@var{function} is run.  That's why @code{(widen)} needs to be called
after @code{save-excursion} and @code{save-restriction} in the example
above.  Also note that with the nnimap backend, message bodies will
not be downloaded by default.  You need to set
@code{nnimap-split-download-body} to @code{t} to do that
(@pxref{Client-Side IMAP Splitting}).

@item (! @var{func} @var{split})
If the split is a list, and the first element is @code{!}, then
@var{split} will be processed, and @var{func} will be called as a
function with the result of @var{split} as argument.  @var{func}
should return a split.

@item nil
If the split is @code{nil}, it is ignored.

@end table

In these splits, @var{field} must match a complete field name.

Normally, @var{value} in these splits must match a complete @emph{word}
according to the fundamental mode syntax table.  In other words, all
@var{value}'s will be implicitly surrounded by @code{\<...\>} markers,
which are word delimiters.  Therefore, if you use the following split,
for example,

@example
(any "joe" "joemail")
@end example

@noindent
messages sent from @samp{joedavis@@foo.org} will normally not be filed
in @samp{joemail}.  If you want to alter this behavior, you can use any
of the following three ways:

@enumerate
@item
@vindex nnmail-split-fancy-match-partial-words
You can set the @code{nnmail-split-fancy-match-partial-words} variable
to non-@code{nil} in order to ignore word boundaries and instead the
match becomes more like a grep.  This variable controls whether partial
words are matched during fancy splitting.  The default value is
@code{nil}.

Note that it influences all @var{value}'s in your split rules.

@item
@var{value} beginning with @code{.*} ignores word boundaries in front of
a word.  Similarly, if @var{value} ends with @code{.*}, word boundaries
in the rear of a word will be ignored.  For example, the @var{value}
@code{"@@example\\.com"} does not match @samp{foo@@example.com} but
@code{".*@@example\\.com"} does.

@item
You can set the @var{invert-partial} flag in your split rules of the
@samp{(@var{field} @var{value} @dots{})} types, aforementioned in this
section.  If the flag is set, word boundaries on both sides of a word
are ignored even if @code{nnmail-split-fancy-match-partial-words} is
@code{nil}.  Contrarily, if the flag is set, word boundaries are not
ignored even if @code{nnmail-split-fancy-match-partial-words} is
non-@code{nil}.  (New in Gnus 5.10.7)
@end enumerate

@vindex nnmail-split-abbrev-alist
@var{field} and @var{value} can also be Lisp symbols, in that case
they are expanded as specified by the variable
@code{nnmail-split-abbrev-alist}.  This is an alist of cons cells,
where the @sc{car} of a cell contains the key, and the @sc{cdr}
contains the associated value.  Predefined entries in
@code{nnmail-split-abbrev-alist} include:

@table @code
@item from
Matches the @samp{From}, @samp{Sender} and @samp{Resent-From} fields.
@item to
Matches the @samp{To}, @samp{Cc}, @samp{Apparently-To},
@samp{Resent-To} and @samp{Resent-Cc} fields.
@item any
Is the union of the @code{from} and @code{to} entries.
@end table

@vindex nnmail-split-fancy-syntax-table
@code{nnmail-split-fancy-syntax-table} is the syntax table in effect
when all this splitting is performed.

If you want to have Gnus create groups dynamically based on some
information in the headers (i.e., do @code{replace-match}-like
substitutions in the group names), you can say things like:

@example
(any "debian-\\b\\(\\w+\\)@@lists.debian.org" "mail.debian.\\1")
@end example

In this example, messages sent to @samp{debian-foo@@lists.debian.org}
will be filed in @samp{mail.debian.foo}.

If the string contains the element @samp{\\&}, then the previously
matched string will be substituted.  Similarly, the elements @samp{\\1}
up to @samp{\\9} will be substituted with the text matched by the
groupings 1 through 9.

@vindex nnmail-split-lowercase-expanded
Where @code{nnmail-split-lowercase-expanded} controls whether the
lowercase of the matched string should be used for the substitution.
Setting it as non-@code{nil} is useful to avoid the creation of multiple
groups when users send to an address using different case
(i.e., mailing-list@@domain vs Mailing-List@@Domain).  The default value
is @code{t}.

@findex nnmail-split-fancy-with-parent
@code{nnmail-split-fancy-with-parent} is a function which allows you to
split followups into the same groups their parents are in.  Sometimes
you can't make splitting rules for all your mail.  For example, your
boss might send you personal mail regarding different projects you are
working on, and as you can't tell your boss to put a distinguishing
string into the subject line, you have to resort to manually moving the
messages into the right group.  With this function, you only have to do
it once per thread.

To use this feature, you have to set @code{nnmail-treat-duplicates}
and @code{nnmail-cache-accepted-message-ids} to a non-@code{nil}
value.  And then you can include @code{nnmail-split-fancy-with-parent}
using the colon feature, like so:
@lisp
(setq nnmail-treat-duplicates 'warn     ; @r{or @code{delete}}
      nnmail-cache-accepted-message-ids t
      nnmail-split-fancy
      '(| (: nnmail-split-fancy-with-parent)
          ;; @r{other splits go here}
        ))
@end lisp

This feature works as follows: when @code{nnmail-treat-duplicates} is
non-@code{nil}, Gnus records the message id of every message it sees
in the file specified by the variable
@code{nnmail-message-id-cache-file}, together with the group it is in
(the group is omitted for non-mail messages).  When mail splitting is
invoked, the function @code{nnmail-split-fancy-with-parent} then looks
at the References (and In-Reply-To) header of each message to split
and searches the file specified by @code{nnmail-message-id-cache-file}
for the message ids.  When it has found a parent, it returns the
corresponding group name unless the group name matches the regexp
@code{nnmail-split-fancy-with-parent-ignore-groups}.  It is
recommended that you set @code{nnmail-message-id-cache-length} to a
somewhat higher number than the default so that the message ids are
still in the cache.  (A value of 5000 appears to create a file some
300 kBytes in size.)
@vindex nnmail-cache-accepted-message-ids
When @code{nnmail-cache-accepted-message-ids} is non-@code{nil}, Gnus
also records the message ids of moved articles, so that the followup
messages goes into the new group.

Also see the variable @code{nnmail-cache-ignore-groups} if you don't
want certain groups to be recorded in the cache.  For example, if all
outgoing messages are written to an ``outgoing'' group, you could set
@code{nnmail-cache-ignore-groups} to match that group name.
Otherwise, answers to all your messages would end up in the
``outgoing'' group.


@node Group Mail Splitting
@subsection Group Mail Splitting
@cindex mail splitting
@cindex group mail splitting

@findex gnus-group-split
If you subscribe to dozens of mailing lists but you don't want to
maintain mail splitting rules manually, group mail splitting is for you.
You just have to set @code{to-list} and/or @code{to-address} in group
parameters or group customization and set @code{nnmail-split-methods} to
@code{gnus-group-split}.  This splitting function will scan all groups
for those parameters and split mail accordingly, i.e., messages posted
from or to the addresses specified in the parameters @code{to-list} or
@code{to-address} of a mail group will be stored in that group.

Sometimes, mailing lists have multiple addresses, and you may want mail
splitting to recognize them all: just set the @code{extra-aliases} group
parameter to the list of additional addresses and it's done.  If you'd
rather use a regular expression, set @code{split-regexp}.

All these parameters in a group will be used to create an
@code{nnmail-split-fancy} split, in which the @var{field} is @samp{any},
the @var{value} is a single regular expression that matches
@code{to-list}, @code{to-address}, all of @code{extra-aliases} and all
matches of @code{split-regexp}, and the @var{split} is the name of the
group.  @var{restrict}s are also supported: just set the
@code{split-exclude} parameter to a list of regular expressions.

If you can't get the right split to be generated using all these
parameters, or you just need something fancier, you can set the
parameter @code{split-spec} to an @code{nnmail-split-fancy} split.  In
this case, all other aforementioned parameters will be ignored by
@code{gnus-group-split}.  In particular, @code{split-spec} may be set to
@code{nil}, in which case the group will be ignored by
@code{gnus-group-split}.

@vindex gnus-group-split-default-catch-all-group
@code{gnus-group-split} will do cross-posting on all groups that match,
by defining a single @code{&} fancy split containing one split for each
group.  If a message doesn't match any split, it will be stored in the
group named in @code{gnus-group-split-default-catch-all-group}, unless
some group has @code{split-spec} set to @code{catch-all}, in which case
that group is used as the catch-all group.  Even though this variable is
often used just to name a group, it may also be set to an arbitrarily
complex fancy split (after all, a group name is a fancy split), and this
may be useful to split mail that doesn't go to any mailing list to
personal mail folders.  Note that this fancy split is added as the last
element of a @code{|} split list that also contains a @code{&} split
with the rules extracted from group parameters.

It's time for an example.  Assume the following group parameters have
been defined:

@example
nnml:mail.bar:
((to-address . "bar@@femail.com")
 (split-regexp . ".*@@femail\\.com"))
nnml:mail.foo:
((to-list . "foo@@nowhere.gov")
 (extra-aliases "foo@@localhost" "foo-redist@@home")
 (split-exclude "bugs-foo" "rambling-foo")
 (admin-address . "foo-request@@nowhere.gov"))
nnml:mail.others:
((split-spec . catch-all))
@end example

Setting @code{nnmail-split-methods} to @code{gnus-group-split} will
behave as if @code{nnmail-split-fancy} had been selected and variable
@code{nnmail-split-fancy} had been set as follows:

@lisp
(| (& (any "\\(bar@@femail\\.com\\|.*@@femail\\.com\\)" "mail.bar")
      (any "\\(foo@@nowhere\\.gov\\|foo@@localhost\\|foo-redist@@home\\)"
           - "bugs-foo" - "rambling-foo" "mail.foo"))
   "mail.others")
@end lisp

@findex gnus-group-split-fancy
If you'd rather not use group splitting for all your mail groups, you
may use it for only some of them, by using @code{nnmail-split-fancy}
splits like this:

@lisp
(: gnus-group-split-fancy @var{groups} @var{no-crosspost} @var{catch-all})
@end lisp

@var{groups} may be a regular expression or a list of group names whose
parameters will be scanned to generate the output split.
@var{no-crosspost} can be used to disable cross-posting; in this case, a
single @code{|} split will be output.  @var{catch-all} is the fall back
fancy split, used like @code{gnus-group-split-default-catch-all-group}.
If @var{catch-all} is @code{nil}, or if @code{split-regexp} matches the
empty string in any selected group, no catch-all split will be issued.
Otherwise, if some group has @code{split-spec} set to @code{catch-all},
this group will override the value of the @var{catch-all} argument.

@findex gnus-group-split-setup
Unfortunately, scanning all groups and their parameters can be quite
slow, especially considering that it has to be done for every message.
But don't despair!  The function @code{gnus-group-split-setup} can be
used to enable @code{gnus-group-split} in a much more efficient way.  It
sets @code{nnmail-split-methods} to @code{nnmail-split-fancy} and sets
@code{nnmail-split-fancy} to the split produced by
@code{gnus-group-split-fancy}.  Thus, the group parameters are only
scanned once, no matter how many messages are split.

@findex gnus-group-split-update
However, if you change group parameters, you'd have to update
@code{nnmail-split-fancy} manually.  You can do it by running
@code{gnus-group-split-update}.  If you'd rather have it updated
automatically, just tell @code{gnus-group-split-setup} to do it for
you.  For example, add to your @file{~/.gnus.el}:

@lisp
(gnus-group-split-setup @var{auto-update} @var{catch-all})
@end lisp

If @var{auto-update} is non-@code{nil}, @code{gnus-group-split-update}
will be added to @code{nnmail-pre-get-new-mail-hook}, so you won't ever
have to worry about updating @code{nnmail-split-fancy} again.  If you
don't omit @var{catch-all} (it's optional, equivalent to @code{nil}),
@code{gnus-group-split-default-catch-all-group} will be set to its
value.

@vindex gnus-group-split-updated-hook
Because you may want to change @code{nnmail-split-fancy} after it is set
by @code{gnus-group-split-update}, this function will run
@code{gnus-group-split-updated-hook} just before finishing.

@node Incorporating Old Mail
@subsection Incorporating Old Mail
@cindex incorporating old mail
@cindex import old mail

Most people have lots of old mail stored in various file formats.  If
you have set up Gnus to read mail using one of the spiffy Gnus mail
back ends, you'll probably wish to have that old mail incorporated into
your mail groups.

Doing so can be quite easy.

To take an example: You're reading mail using @code{nnml}
(@pxref{Mail Spool}), and have set @code{nnmail-split-methods} to a
satisfactory value (@pxref{Splitting Mail}).  You have an old Unix mbox
file filled with important, but old, mail.  You want to move it into
your @code{nnml} groups.

Here's how:

@enumerate
@item
Go to the group buffer.

@item
Type @kbd{G f} and give the file name to the mbox file when prompted to create an
@code{nndoc} group from the mbox file (@pxref{Foreign Groups}).

@item
Type @kbd{SPACE} to enter the newly created group.

@item
Type @kbd{M P b} to process-mark all articles in this group's buffer
(@pxref{Setting Process Marks}).

@item
Type @kbd{B r} to respool all the process-marked articles, and answer
@samp{nnml} when prompted (@pxref{Mail Group Commands}).
@end enumerate

All the mail messages in the mbox file will now also be spread out over
all your @code{nnml} groups.  Try entering them and check whether things
have gone without a glitch.  If things look ok, you may consider
deleting the mbox file, but I wouldn't do that unless I was absolutely
sure that all the mail has ended up where it should be.

Respooling is also a handy thing to do if you're switching from one mail
back end to another.  Just respool all the mail in the old mail groups
using the new mail back end.


@node Expiring Mail
@subsection Expiring Mail
@cindex article expiry
@cindex expiring mail

Traditional mail readers have a tendency to remove mail articles when
you mark them as read, in some way.  Gnus takes a fundamentally
different approach to mail reading.

Gnus basically considers mail just to be news that has been received in
a rather peculiar manner.  It does not think that it has the power to
actually change the mail, or delete any mail messages.  If you enter a
mail group, and mark articles as ``read'', or kill them in some other
fashion, the mail articles will still exist on the system.  I repeat:
Gnus will not delete your old, read mail.  Unless you ask it to, of
course.

To make Gnus get rid of your unwanted mail, you have to mark the
articles as @dfn{expirable}.  (With the default key bindings, this means
that you have to type @kbd{E}.)  This does not mean that the articles
will disappear right away, however.  In general, a mail article will be
deleted from your system if, 1) it is marked as expirable, AND 2) it is
more than one week old.  If you do not mark an article as expirable, it
will remain on your system until hell freezes over.  This bears
repeating one more time, with some spurious capitalizations: IF you do
NOT mark articles as EXPIRABLE, Gnus will NEVER delete those ARTICLES.

@vindex gnus-auto-expirable-marks
You do not have to mark articles as expirable by hand.  Gnus provides
two features, called ``auto-expire'' and ``total-expire'', that can help you
with this.  In a nutshell, ``auto-expire'' means that Gnus hits @kbd{E}
for you when you select an article.  And ``total-expire'' means that Gnus
considers all articles as expirable that are read.  So, in addition to
the articles marked @samp{E}, also the articles marked @samp{r},
@samp{R}, @samp{O}, @samp{K}, @samp{Y} (and so on) are considered
expirable.  @code{gnus-auto-expirable-marks} has the full list of
these marks.

When should either auto-expire or total-expire be used?  Most people
who are subscribed to mailing lists split each list into its own group
and then turn on auto-expire or total-expire for those groups.
(@xref{Splitting Mail}, for more information on splitting each list
into its own group.)

Which one is better, auto-expire or total-expire?  It's not easy to
answer.  Generally speaking, auto-expire is probably faster.  Another
advantage of auto-expire is that you get more marks to work with: for
the articles that are supposed to stick around, you can still choose
between tick and dormant and read marks.  But with total-expire, you
only have dormant and ticked to choose from.  The advantage of
total-expire is that it works well with adaptive scoring (@pxref{Adaptive
Scoring}).  Auto-expire works with normal scoring but not with adaptive
scoring.

@vindex gnus-auto-expirable-newsgroups
Groups that match the regular expression
@code{gnus-auto-expirable-newsgroups} will have all articles that you
read marked as expirable automatically.  All articles marked as
expirable have an @samp{E} in the first column in the summary buffer.

By default, if you have auto expiry switched on, Gnus will mark all the
articles you read as expirable, no matter if they were read or unread
before.  To avoid having articles marked as read marked as expirable
automatically, you can put something like the following in your
@file{~/.gnus.el} file:

@vindex gnus-mark-article-hook
@lisp
(remove-hook 'gnus-mark-article-hook
             'gnus-summary-mark-read-and-unread-as-read)
(add-hook 'gnus-mark-article-hook 'gnus-summary-mark-unread-as-read)
@end lisp

Note that making a group auto-expirable doesn't mean that all read
articles are expired---only the articles marked as expirable
will be expired.  Also note that using the @kbd{d} command won't make
articles expirable---only semi-automatic marking of articles as read will
mark the articles as expirable in auto-expirable groups.

Let's say you subscribe to a couple of mailing lists, and you want the
articles you have read to disappear after a while:

@lisp
(setq gnus-auto-expirable-newsgroups
      "mail.nonsense-list\\|mail.nice-list")
@end lisp

Another way to have auto-expiry happen is to have the element
@code{auto-expire} in the group parameters of the group.

If you use adaptive scoring (@pxref{Adaptive Scoring}) and
auto-expiring, you'll have problems.  Auto-expiring and adaptive scoring
don't really mix very well.

@vindex nnmail-expiry-wait
The @code{nnmail-expiry-wait} variable supplies the default time an
expirable article has to live.  Gnus starts counting days from when the
message @emph{arrived}, not from when it was sent.  The default is seven
days.

Gnus also supplies a function that lets you fine-tune how long articles
are to live, based on what group they are in.  Let's say you want to
have one month expiry period in the @samp{mail.private} group, a one day
expiry period in the @samp{mail.junk} group, and a six day expiry period
everywhere else:

@vindex nnmail-expiry-wait-function
@lisp
(setq nnmail-expiry-wait-function
      (lambda (group)
       (cond ((string= group "mail.private")
               31)
             ((string= group "mail.junk")
               1)
             ((string= group "important")
               'never)
             (t
               6))))
@end lisp

The group names this function is fed are ``unadorned'' group
names---no @samp{nnml:} prefixes and the like.

The @code{nnmail-expiry-wait} variable and
@code{nnmail-expiry-wait-function} function can either be a number (not
necessarily an integer) or one of the symbols @code{immediate} or
@code{never}.

You can also use the @code{expiry-wait} group parameter to selectively
change the expiry period (@pxref{Group Parameters}).

@vindex nnmail-expiry-target
The normal action taken when expiring articles is to delete them.
However, in some circumstances it might make more sense to move them
to other groups instead of deleting them.  The variable
@code{nnmail-expiry-target} (and the @code{expiry-target} group
parameter) controls this.  The variable supplies a default value for
all groups, which can be overridden for specific groups by the group
parameter.  default value is @code{delete}, but this can also be a
string (which should be the name of the group the message should be
moved to), or a function (which will be called in a buffer narrowed to
the message in question, and with the name of the group being moved
from as its parameter) which should return a target---either a group
name or @code{delete}.

Here's an example for specifying a group name:
@lisp
(setq nnmail-expiry-target "nnml:expired")
@end lisp

@findex nnmail-fancy-expiry-target
@vindex nnmail-fancy-expiry-targets
Gnus provides a function @code{nnmail-fancy-expiry-target} which will
expire mail to groups according to the variable
@code{nnmail-fancy-expiry-targets}.  Here's an example:

@lisp
 (setq nnmail-expiry-target 'nnmail-fancy-expiry-target
       nnmail-fancy-expiry-targets
       '((to-from "boss" "nnfolder:Work")
         ("subject" "IMPORTANT" "nnfolder:IMPORTANT.%Y.%b")
         ("from" ".*" "nnfolder:Archive-%Y")))
@end lisp

With this setup, any mail that has @code{IMPORTANT} in its Subject
header and was sent in the year @code{YYYY} and month @code{MMM}, will
get expired to the group @code{nnfolder:IMPORTANT.YYYY.MMM}.  If its
From or To header contains the string @code{boss}, it will get expired
to @code{nnfolder:Work}.  All other mail will get expired to
@code{nnfolder:Archive-YYYY}.

@vindex nnmail-keep-last-article
If @code{nnmail-keep-last-article} is non-@code{nil}, Gnus will never
expire the final article in a mail newsgroup.  This is to make life
easier for procmail users.

@vindex gnus-total-expirable-newsgroups
By the way: That line up there, about Gnus never expiring non-expirable
articles, is a lie.  If you put @code{total-expire} in the group
parameters, articles will not be marked as expirable, but all read
articles will be put through the expiry process.  Use with extreme
caution.  Even more dangerous is the
@code{gnus-total-expirable-newsgroups} variable.  All groups that match
this regexp will have all read articles put through the expiry process,
which means that @emph{all} old mail articles in the groups in question
will be deleted after a while.  Use with extreme caution, and don't come
crying to me when you discover that the regexp you used matched the
wrong group and all your important mail has disappeared.  Be a
@emph{man}!  Or a @emph{woman}!  Whatever you feel more comfortable
with!  So there!

Most people make most of their mail groups total-expirable, though.

@vindex gnus-inhibit-user-auto-expire
If @code{gnus-inhibit-user-auto-expire} is non-@code{nil}, user marking
commands will not mark an article as expirable, even if the group has
auto-expire turned on.

@vindex gnus-mark-copied-or-moved-articles-as-expirable
The expirable marks of articles will be removed when copying or moving
them to a group in which auto-expire is not turned on.  This is for
preventing articles from being expired unintentionally.  On the other
hand, to a group that has turned auto-expire on, the expirable marks of
articles that are copied or moved will not be changed by default.  I.e.,
when copying or moving to such a group, articles that were expirable
will be left expirable and ones that were not expirable will not be
marked as expirable.  So, even though in auto-expire groups, some
articles will never get expired (unless you read them again).  If you
don't side with that behavior that unexpirable articles may be mixed
into auto-expire groups, you can set
@code{gnus-mark-copied-or-moved-articles-as-expirable} to a
non-@code{nil} value.  In that case, articles that have been read will
be marked as expirable automatically when being copied or moved to a
group that has auto-expire turned on.  The default value is @code{nil}.


@node Washing Mail
@subsection Washing Mail
@cindex mail washing
@cindex list server brain damage
@cindex incoming mail treatment

Mailers and list servers are notorious for doing all sorts of really,
really stupid things with mail.  ``Hey, RFC 822 doesn't explicitly
prohibit us from adding the string @code{wE aRe ElItE!!!!!1!!} to the
end of all lines passing through our server, so let's do that!!!!1!''
Yes, but RFC 822 wasn't designed to be read by morons.  Things that were
considered to be self-evident were not discussed.  So.  Here we are.

Case in point:  The German version of Microsoft Exchange adds @samp{AW:
} to the subjects of replies instead of @samp{Re: }.  I could pretend to
be shocked and dismayed by this, but I haven't got the energy.  It is to
laugh.

Gnus provides a plethora of functions for washing articles while
displaying them, but it might be nicer to do the filtering before
storing the mail to disk.  For that purpose, we have three hooks and
various functions that can be put in these hooks.

@table @code
@item nnmail-prepare-incoming-hook
@vindex nnmail-prepare-incoming-hook
This hook is called before doing anything with the mail and is meant for
grand, sweeping gestures.  It is called in a buffer that contains all
the new, incoming mail.  Functions to be used include:

@table @code
@item nnheader-ms-strip-cr
@findex nnheader-ms-strip-cr
Remove trailing carriage returns from each line.  This is default on
Emacs running on MS machines.

@end table

@item nnmail-prepare-incoming-header-hook
@vindex nnmail-prepare-incoming-header-hook
This hook is called narrowed to each header.  It can be used when
cleaning up the headers.  Functions that can be used include:

@table @code
@item nnmail-remove-leading-whitespace
@findex nnmail-remove-leading-whitespace
Clear leading white space that ``helpful'' listservs have added to the
headers to make them look nice.  Aaah.

(Note that this function works on both the header on the body of all
messages, so it is a potentially dangerous function to use (if a body
of a message contains something that looks like a header line).  So
rather than fix the bug, it is of course the right solution to make it
into a feature by documenting it.)

@item nnmail-remove-list-identifiers
@findex nnmail-remove-list-identifiers
Some list servers add an identifier---for example, @samp{(idm)}---to the
beginning of all @code{Subject} headers.  I'm sure that's nice for
people who use stone age mail readers.  This function will remove
strings that match the @code{nnmail-list-identifiers} regexp, which can
also be a list of regexp.  @code{nnmail-list-identifiers} may not contain
@code{\\(..\\)}.

For instance, if you want to remove the @samp{(idm)} and the
@samp{nagnagnag} identifiers:

@lisp
(setq nnmail-list-identifiers
      '("(idm)" "nagnagnag"))
@end lisp

This can also be done non-destructively with
@code{gnus-list-identifiers}, @xref{Article Hiding}.

@item nnmail-remove-tabs
@findex nnmail-remove-tabs
Translate all @samp{TAB} characters into @samp{SPACE} characters.

@item nnmail-ignore-broken-references
@findex nnmail-ignore-broken-references
@c @findex nnmail-fix-eudora-headers
@cindex Eudora
@cindex Pegasus
Some mail user agents (e.g., Eudora and Pegasus) produce broken
@code{References} headers, but correct @code{In-Reply-To} headers.  This
function will get rid of the @code{References} header if the headers
contain a line matching the regular expression
@code{nnmail-broken-references-mailers}.

@end table

@item nnmail-prepare-incoming-message-hook
@vindex nnmail-prepare-incoming-message-hook
This hook is called narrowed to each message.  Functions to be used
include:

@table @code
@item article-de-quoted-unreadable
@findex article-de-quoted-unreadable
Decode Quoted Readable encoding.

@end table
@end table


@node Duplicates
@subsection Duplicates

@vindex nnmail-treat-duplicates
@vindex nnmail-message-id-cache-length
@vindex nnmail-message-id-cache-file
@cindex duplicate mails
If you are a member of a couple of mailing lists, you will sometimes
receive two copies of the same mail.  This can be quite annoying, so
@code{nnmail} checks for and treats any duplicates it might find.  To do
this, it keeps a cache of old @code{Message-ID}s:
@code{nnmail-message-id-cache-file}, which is @file{~/.nnmail-cache} by
default.  The approximate maximum number of @code{Message-ID}s stored
there is controlled by the @code{nnmail-message-id-cache-length}
variable, which is 1000 by default.  (So 1000 @code{Message-ID}s will be
stored.) If all this sounds scary to you, you can set
@code{nnmail-treat-duplicates} to @code{warn} (which is what it is by
default), and @code{nnmail} won't delete duplicate mails.  Instead it
will insert a warning into the head of the mail saying that it thinks
that this is a duplicate of a different message.

This variable can also be a function.  If that's the case, the function
will be called from a buffer narrowed to the message in question with
the @code{Message-ID} as a parameter.  The function must return either
@code{nil}, @code{warn}, or @code{delete}.

You can turn this feature off completely by setting the variable to
@code{nil}.

If you want all the duplicate mails to be put into a special
@dfn{duplicates} group, you could do that using the normal mail split
methods:

@lisp
(setq nnmail-split-fancy
      '(| ;; @r{Messages duplicates go to a separate group.}
        ("gnus-warning" "duplicat\\(e\\|ion\\) of message" "duplicate")
        ;; @r{Message from daemons, postmaster, and the like to another.}
        (any mail "mail.misc")
        ;; @r{Other rules.}
        [...] ))
@end lisp
@noindent
Or something like:
@lisp
(setq nnmail-split-methods
      '(("duplicates" "^Gnus-Warning:.*duplicate")
        ;; @r{Other rules.}
        [...]))
@end lisp

Here's a neat feature: If you know that the recipient reads her mail
with Gnus, and that she has @code{nnmail-treat-duplicates} set to
@code{delete}, you can send her as many insults as you like, just by
using a @code{Message-ID} of a mail that you know that she's already
received.  Think of all the fun!  She'll never see any of it!  Whee!


@node Not Reading Mail
@subsection Not Reading Mail

If you start using any of the mail back ends, they have the annoying
habit of assuming that you want to read mail with them.  This might not
be unreasonable, but it might not be what you want.

If you set @code{mail-sources} and @code{nnmail-spool-file} to
@code{nil}, none of the back ends will ever attempt to read incoming
mail, which should help.

@vindex nnbabyl-get-new-mail
@vindex nnmbox-get-new-mail
@vindex nnml-get-new-mail
@vindex nnmh-get-new-mail
@vindex nnfolder-get-new-mail
This might be too much, if, for instance, you are reading mail quite
happily with @code{nnml} and just want to peek at some old (pre-Emacs
23) Rmail file you have stashed away with @code{nnbabyl}.  All back ends have
variables called back-end-@code{get-new-mail}.  If you want to disable
the @code{nnbabyl} mail reading, you edit the virtual server for the
group to have a setting where @code{nnbabyl-get-new-mail} to @code{nil}.

All the mail back ends will call @code{nn}*@code{-prepare-save-mail-hook}
narrowed to the article to be saved before saving it when reading
incoming mail.


@node Choosing a Mail Back End
@subsection Choosing a Mail Back End

Gnus will read the mail spool when you activate a mail group.  The mail
file is first copied to your home directory.  What happens after that
depends on what format you want to store your mail in.

There are six different mail back ends in the standard Gnus, and more
back ends are available separately.  The mail back end most people use
(because it is possibly the fastest) is @code{nnml} (@pxref{Mail
Spool}).

@menu
* Unix Mail Box::               Using the (quite) standard Un*x mbox.
* Babyl::                       Babyl was used by older versions of Rmail.
* Mail Spool::                  Store your mail in a private spool?
* MH Spool::                    An mhspool-like back end.
* Maildir::                     Another one-file-per-message format.
* nnmaildir Group Parameters::
* Article Identification::
* NOV Data::
* Article Marks::
* Mail Folders::                Having one file for each group.
* Comparing Mail Back Ends::    An in-depth looks at pros and cons.
@end menu



@node Unix Mail Box
@subsubsection Unix Mail Box
@cindex nnmbox
@cindex unix mail box

@vindex nnmbox-active-file
@vindex nnmbox-mbox-file
The @dfn{nnmbox} back end will use the standard Un*x mbox file to store
mail.  @code{nnmbox} will add extra headers to each mail article to say
which group it belongs in.

Virtual server settings:

@table @code
@item nnmbox-mbox-file
@vindex nnmbox-mbox-file
The name of the mail box in the user's home directory.  Default is
@file{~/mbox}.

@item nnmbox-active-file
@vindex nnmbox-active-file
The name of the active file for the mail box.  Default is
@file{~/.mbox-active}.

@item nnmbox-get-new-mail
@vindex nnmbox-get-new-mail
If non-@code{nil}, @code{nnmbox} will read incoming mail and split it
into groups.  Default is @code{t}.
@end table


@node Babyl
@subsubsection Babyl
@cindex nnbabyl

@vindex nnbabyl-active-file
@vindex nnbabyl-mbox-file
The @dfn{nnbabyl} back end will use a Babyl mail box to store mail.
@code{nnbabyl} will add extra headers to each mail article to say which
group it belongs in.

Virtual server settings:

@table @code
@item nnbabyl-mbox-file
@vindex nnbabyl-mbox-file
The name of the Babyl file.  The default is @file{~/RMAIL}

@item nnbabyl-active-file
@vindex nnbabyl-active-file
The name of the active file for the Babyl file.  The default is
@file{~/.rmail-active}

@item nnbabyl-get-new-mail
@vindex nnbabyl-get-new-mail
If non-@code{nil}, @code{nnbabyl} will read incoming mail.  Default is
@code{t}
@end table


@node Mail Spool
@subsubsection Mail Spool
@cindex nnml
@cindex mail @acronym{NOV} spool

The @dfn{nnml} spool mail format isn't compatible with any other known
format.  It should be used with some caution.

@vindex nnml-directory
If you use this back end, Gnus will split all incoming mail into files,
one file for each mail, and put the articles into the corresponding
directories under the directory specified by the @code{nnml-directory}
variable.  The default value is @file{~/Mail/}.

You do not have to create any directories beforehand; Gnus will take
care of all that.

If you have a strict limit as to how many files you are allowed to store
in your account, you should not use this back end.  As each mail gets its
own file, you might very well occupy thousands of inodes within a few
weeks.  If this is no problem for you, and it isn't a problem for you
having your friendly systems administrator walking around, madly,
shouting ``Who is eating all my inodes?! Who? Who!?!'', then you should
know that this is probably the fastest format to use.  You do not have
to trudge through a big mbox file just to read your new mail.

@code{nnml} is probably the slowest back end when it comes to article
splitting.  It has to create lots of files, and it also generates
@acronym{NOV} databases for the incoming mails.  This makes it possibly the
fastest back end when it comes to reading mail.

Virtual server settings:

@table @code
@item nnml-directory
@vindex nnml-directory
All @code{nnml} directories will be placed under this directory.  The
default is the value of @code{message-directory} (whose default value
is @file{~/Mail}).

@item nnml-active-file
@vindex nnml-active-file
The active file for the @code{nnml} server.  The default is
@file{~/Mail/active}.

@item nnml-newsgroups-file
@vindex nnml-newsgroups-file
The @code{nnml} group descriptions file.  @xref{Newsgroups File
Format}.  The default is @file{~/Mail/newsgroups}.

@item nnml-get-new-mail
@vindex nnml-get-new-mail
If non-@code{nil}, @code{nnml} will read incoming mail.  The default is
@code{t}.

@item nnml-nov-is-evil
@vindex nnml-nov-is-evil
If non-@code{nil}, this back end will ignore any @acronym{NOV} files.  The
default is @code{nil}.

@item nnml-nov-file-name
@vindex nnml-nov-file-name
The name of the @acronym{NOV} files.  The default is @file{.overview}.

@item nnml-prepare-save-mail-hook
@vindex nnml-prepare-save-mail-hook
Hook run narrowed to an article before saving.

@item nnml-use-compressed-files
@vindex nnml-use-compressed-files
If non-@code{nil}, @code{nnml} will allow using compressed message
files.  This requires @code{auto-compression-mode} to be enabled
(@pxref{Compressed Files, ,Compressed Files, emacs, The Emacs Manual}).
If the value of @code{nnml-use-compressed-files} is a string, it is used
as the file extension specifying the compression program.  You can set it
to @samp{.bz2} if your Emacs supports it.  A value of @code{t} is
equivalent to @samp{.gz}.

@item nnml-compressed-files-size-threshold
@vindex nnml-compressed-files-size-threshold
Default size threshold for compressed message files.  Message files with
bodies larger than that many characters will be automatically compressed
if @code{nnml-use-compressed-files} is non-@code{nil}.

@end table

@findex nnml-generate-nov-databases
If your @code{nnml} groups and @acronym{NOV} files get totally out of
whack, you can do a complete update by typing @kbd{M-x
nnml-generate-nov-databases}.  This command will trawl through the
entire @code{nnml} hierarchy, looking at each and every article, so it
might take a while to complete.  A better interface to this
functionality can be found in the server buffer (@pxref{Server
Commands}).


@node MH Spool
@subsubsection MH Spool
@cindex nnmh
@cindex mh-e mail spool

@code{nnmh} is just like @code{nnml}, except that is doesn't generate
@acronym{NOV} databases and it doesn't keep an active file or marks
file.  This makes @code{nnmh} a @emph{much} slower back end than
@code{nnml}, but it also makes it easier to write procmail scripts
for.

Virtual server settings:

@table @code
@item nnmh-directory
@vindex nnmh-directory
All @code{nnmh} directories will be located under this directory.  The
default is the value of @code{message-directory} (whose default is
@file{~/Mail})

@item nnmh-get-new-mail
@vindex nnmh-get-new-mail
If non-@code{nil}, @code{nnmh} will read incoming mail.  The default is
@code{t}.

@item nnmh-be-safe
@vindex nnmh-be-safe
If non-@code{nil}, @code{nnmh} will go to ridiculous lengths to make
sure that the articles in the folder are actually what Gnus thinks
they are.  It will check date stamps and stat everything in sight, so
setting this to @code{t} will mean a serious slow-down.  If you never
use anything but Gnus to read the @code{nnmh} articles, you do not
have to set this variable to @code{t}.  The default is @code{nil}.
@end table


@node Maildir
@subsubsection Maildir
@cindex nnmaildir
@cindex maildir

@code{nnmaildir} stores mail in the maildir format, with each maildir
corresponding to a group in Gnus.  This format is documented here:
@uref{http://cr.yp.to/proto/maildir.html} and here:
@uref{http://www.qmail.org/man/man5/maildir.html}.  @code{nnmaildir}
also stores extra information in the @file{.nnmaildir/} directory
within a maildir.

Maildir format was designed to allow concurrent deliveries and
reading, without needing locks.  With other back ends, you would have
your mail delivered to a spool of some kind, and then you would
configure Gnus to split mail from that spool into your groups.  You
can still do that with @code{nnmaildir}, but the more common
configuration is to have your mail delivered directly to the maildirs
that appear as group in Gnus.

@code{nnmaildir} is designed to be perfectly reliable: @kbd{C-g} will
never corrupt its data in memory, and @code{SIGKILL} will never
corrupt its data in the filesystem.

@code{nnmaildir} stores article marks and @acronym{NOV} data in each
maildir.  So you can copy a whole maildir from one Gnus setup to
another, and you will keep your marks.

Virtual server settings:

@table @code
@item directory
For each of your @code{nnmaildir} servers (it's very unlikely that
you'd need more than one), you need to create a directory and populate
it with maildirs or symlinks to maildirs (and nothing else; do not
choose a directory already used for other purposes).  Each maildir
will be represented in Gnus as a newsgroup on that server; the
filename of the symlink will be the name of the group.  Any filenames
in the directory starting with @samp{.} are ignored.  The directory is
scanned when you first start Gnus, and each time you type @kbd{g} in
the group buffer; if any maildirs have been removed or added,
@code{nnmaildir} notices at these times.

The value of the @code{directory} parameter should be a Lisp form
which is processed by @code{eval} and @code{expand-file-name} to get
the path of the directory for this server.  The form is @code{eval}ed
only when the server is opened; the resulting string is used until the
server is closed.  (If you don't know about forms and @code{eval},
don't worry---a simple string will work.)  This parameter is not
optional; you must specify it.  I don't recommend using
@code{"~/Mail"} or a subdirectory of it; several other parts of Gnus
use that directory by default for various things, and may get confused
if @code{nnmaildir} uses it too.  @code{"~/.nnmaildir"} is a typical
value.

@item target-prefix
This should be a Lisp form which is processed by @code{eval} and
@code{expand-file-name}.  The form is @code{eval}ed only when the
server is opened; the resulting string is used until the server is
closed.

When you create a group on an @code{nnmaildir} server, the maildir is
created with @code{target-prefix} prepended to its name, and a symlink
pointing to that maildir is created, named with the plain group name.
So if @code{directory} is @code{"~/.nnmaildir"} and
@code{target-prefix} is @code{"../maildirs/"}, then when you create
the group @code{foo}, @code{nnmaildir} will create
@file{~/.nnmaildir/../maildirs/foo} as a maildir, and will create
@file{~/.nnmaildir/foo} as a symlink pointing to
@file{../maildirs/foo}.

You can set @code{target-prefix} to a string without any slashes to
create both maildirs and symlinks in the same @code{directory}; in
this case, any maildirs found in @code{directory} whose names start
with @code{target-prefix} will not be listed as groups (but the
symlinks pointing to them will be).

As a special case, if @code{target-prefix} is @code{""} (the default),
then when you create a group, the maildir will be created in
@code{directory} without a corresponding symlink.  Beware that you
cannot use @code{gnus-group-delete-group} on such groups without the
@code{force} argument.

@item directory-files
This should be a function with the same interface as
@code{directory-files} (such as @code{directory-files} itself).  It is
used to scan the server's @code{directory} for maildirs.  This
parameter is optional; the default is
@code{nnheader-directory-files-safe} if
@code{nnheader-directory-files-is-safe} is @code{nil}, and
@code{directory-files} otherwise.
(@code{nnheader-directory-files-is-safe} is checked only once when the
server is opened; if you want to check it each time the directory is
scanned, you'll have to provide your own function that does that.)

@item get-new-mail
If non-@code{nil}, then after scanning for new mail in the group
maildirs themselves as usual, this server will also incorporate mail
the conventional Gnus way, from @code{mail-sources} according to
@code{nnmail-split-methods} or @code{nnmail-split-fancy}.  The default
value is @code{nil}.

Do @emph{not} use the same maildir both in @code{mail-sources} and as
an @code{nnmaildir} group.  The results might happen to be useful, but
that would be by chance, not by design, and the results might be
different in the future.  If your split rules create new groups,
remember to supply a @code{create-directory} server parameter.
@end table

@node nnmaildir Group Parameters
@subsubsection Group parameters

@code{nnmaildir} uses several group parameters.  It's safe to ignore
all this; the default behavior for @code{nnmaildir} is the same as the
default behavior for other mail back ends: articles are deleted after
one week, etc.  Except for the expiry parameters, all this
functionality is unique to @code{nnmaildir}, so you can ignore it if
you're just trying to duplicate the behavior you already have with
another back end.

If the value of any of these parameters is a vector, the first element
is evaluated as a Lisp form and the result is used, rather than the
original value.  If the value is not a vector, the value itself is
evaluated as a Lisp form.  (This is why these parameters use names
different from those of other, similar parameters supported by other
back ends: they have different, though similar, meanings.)  (For
numbers, strings, @code{nil}, and @code{t}, you can ignore the
@code{eval} business again; for other values, remember to use an extra
quote and wrap the value in a vector when appropriate.)

@table @code
@item expire-age
An integer specifying the minimum age, in seconds, of an article
before it will be expired, or the symbol @code{never} to specify that
articles should never be expired.  If this parameter is not set,
@code{nnmaildir} falls back to the usual
@code{nnmail-expiry-wait}(@code{-function}) variables (the
@code{expiry-wait} group parameter overrides @code{nnmail-expiry-wait}
and makes @code{nnmail-expiry-wait-function} ineffective).  If you
wanted a value of 3 days, you could use something like @code{[(* 3 24
60 60)]}; @code{nnmaildir} will evaluate the form and use the result.
An article's age is measured starting from the article file's
modification time.  Normally, this is the same as the article's
delivery time, but editing an article makes it younger.  Moving an
article (other than via expiry) may also make an article younger.

@item expire-group
If this is set to a string such as a full Gnus group name, like
@example
"backend+server.address.string:group.name"
@end example
and if it is not the name of the same group that the parameter belongs
to, then articles will be moved to the specified group during expiry
before being deleted.  @emph{If this is set to an @code{nnmaildir}
group, the article will be just as old in the destination group as it
was in the source group.}  So be careful with @code{expire-age} in the
destination group.  If this is set to the name of the same group that
the parameter belongs to, then the article is not expired at all.  If
you use the vector form, the first element is evaluated once for each
article.  So that form can refer to
@code{nnmaildir-article-file-name}, etc., to decide where to put the
article.  @emph{Even if this parameter is not set, @code{nnmaildir}
does not fall back to the @code{expiry-target} group parameter or the
@code{nnmail-expiry-target} variable.}

@item read-only
If this is set to @code{t}, @code{nnmaildir} will treat the articles
in this maildir as read-only.  This means: articles are not renamed
from @file{new/} into @file{cur/}; articles are only found in
@file{new/}, not @file{cur/}; articles are never deleted; articles
cannot be edited.  @file{new/} is expected to be a symlink to the
@file{new/} directory of another maildir---e.g., a system-wide mailbox
containing a mailing list of common interest.  Everything in the
maildir outside @file{new/} is @emph{not} treated as read-only, so for
a shared mailbox, you do still need to set up your own maildir (or
have write permission to the shared mailbox); your maildir just won't
contain extra copies of the articles.

@item directory-files
A function with the same interface as @code{directory-files}.  It is
used to scan the directories in the maildir corresponding to this
group to find articles.  The default is the function specified by the
server's @code{directory-files} parameter.

@item distrust-Lines:
If non-@code{nil}, @code{nnmaildir} will always count the lines of an
article, rather than use the @code{Lines:} header field.  If
@code{nil}, the header field will be used if present.

@item always-marks
A list of mark symbols, such as @code{['(read expire)]}.  Whenever
Gnus asks @code{nnmaildir} for article marks, @code{nnmaildir} will
say that all articles have these marks, regardless of whether the
marks stored in the filesystem say so.  This is a proof-of-concept
feature that will probably be removed eventually; it ought to be done
in Gnus proper, or abandoned if it's not worthwhile.

@item never-marks
A list of mark symbols, such as @code{['(tick expire)]}.  Whenever
Gnus asks @code{nnmaildir} for article marks, @code{nnmaildir} will
say that no articles have these marks, regardless of whether the marks
stored in the filesystem say so.  @code{never-marks} overrides
@code{always-marks}.  This is a proof-of-concept feature that will
probably be removed eventually; it ought to be done in Gnus proper, or
abandoned if it's not worthwhile.

@item nov-cache-size
An integer specifying the size of the @acronym{NOV} memory cache.  To
speed things up, @code{nnmaildir} keeps @acronym{NOV} data in memory
for a limited number of articles in each group.  (This is probably not
worthwhile, and will probably be removed in the future.)  This
parameter's value is noticed only the first time a group is seen after
the server is opened---i.e., when you first start Gnus, typically.
The @acronym{NOV} cache is never resized until the server is closed
and reopened.  The default is an estimate of the number of articles
that would be displayed in the summary buffer: a count of articles
that are either marked with @code{tick} or not marked with
@code{read}, plus a little extra.
@end table

@node Article Identification
@subsubsection Article identification
Articles are stored in the @file{cur/} subdirectory of each maildir.
Each article file is named like @code{uniq:info}, where @code{uniq}
contains no colons.  @code{nnmaildir} ignores, but preserves, the
@code{:info} part.  (Other maildir readers typically use this part of
the filename to store marks.)  The @code{uniq} part uniquely
identifies the article, and is used in various places in the
@file{.nnmaildir/} subdirectory of the maildir to store information
about the corresponding article.  The full pathname of an article is
available in the variable @code{nnmaildir-article-file-name} after you
request the article in the summary buffer.

@node NOV Data
@subsubsection NOV data
An article identified by @code{uniq} has its @acronym{NOV} data (used
to generate lines in the summary buffer) stored in
@code{.nnmaildir/nov/uniq}.  There is no
@code{nnmaildir-generate-nov-databases} function.  (There isn't much
need for it---an article's @acronym{NOV} data is updated automatically
when the article or @code{nnmail-extra-headers} has changed.)  You can
force @code{nnmaildir} to regenerate the @acronym{NOV} data for a
single article simply by deleting the corresponding @acronym{NOV}
file, but @emph{beware}: this will also cause @code{nnmaildir} to
assign a new article number for this article, which may cause trouble
with @code{seen} marks, the Agent, and the cache.

@node Article Marks
@subsubsection Article marks
An article identified by @code{uniq} is considered to have the mark
@code{flag} when the file @file{.nnmaildir/marks/flag/uniq} exists.
When Gnus asks @code{nnmaildir} for a group's marks, @code{nnmaildir}
looks for such files and reports the set of marks it finds.  When Gnus
asks @code{nnmaildir} to store a new set of marks, @code{nnmaildir}
creates and deletes the corresponding files as needed.  (Actually,
rather than create a new file for each mark, it just creates hard
links to @file{.nnmaildir/markfile}, to save inodes.)

You can invent new marks by creating a new directory in
@file{.nnmaildir/marks/}.  You can tar up a maildir and remove it from
your server, untar it later, and keep your marks.  You can add and
remove marks yourself by creating and deleting mark files.  If you do
this while Gnus is running and your @code{nnmaildir} server is open,
it's best to exit all summary buffers for @code{nnmaildir} groups and
type @kbd{s} in the group buffer first, and to type @kbd{g} or
@kbd{M-g} in the group buffer afterwards.  Otherwise, Gnus might not
pick up the changes, and might undo them.


@node Mail Folders
@subsubsection Mail Folders
@cindex nnfolder
@cindex mbox folders
@cindex mail folders

@code{nnfolder} is a back end for storing each mail group in a
separate file.  Each file is in the standard Un*x mbox format.
@code{nnfolder} will add extra headers to keep track of article
numbers and arrival dates.

Virtual server settings:

@table @code
@item nnfolder-directory
@vindex nnfolder-directory
All the @code{nnfolder} mail boxes will be stored under this
directory.  The default is the value of @code{message-directory}
(whose default is @file{~/Mail})

@item nnfolder-active-file
@vindex nnfolder-active-file
The name of the active file.  The default is @file{~/Mail/active}.

@item nnfolder-newsgroups-file
@vindex nnfolder-newsgroups-file
The name of the group descriptions file.  @xref{Newsgroups File
Format}.  The default is @file{~/Mail/newsgroups}

@item nnfolder-get-new-mail
@vindex nnfolder-get-new-mail
If non-@code{nil}, @code{nnfolder} will read incoming mail.  The
default is @code{t}

@item nnfolder-save-buffer-hook
@vindex nnfolder-save-buffer-hook
@cindex backup files
Hook run before saving the folders.  Note that Emacs does the normal
backup renaming of files even with the @code{nnfolder} buffers.  If
you wish to switch this off, you could say something like the
following in your @file{.emacs} file:

@lisp
(defun turn-off-backup ()
  (set (make-local-variable 'backup-inhibited) t))

(add-hook 'nnfolder-save-buffer-hook 'turn-off-backup)
@end lisp

@item nnfolder-delete-mail-hook
@vindex nnfolder-delete-mail-hook
Hook run in a buffer narrowed to the message that is to be deleted.
This function can be used to copy the message to somewhere else, or to
extract some information from it before removing it.

@item nnfolder-nov-is-evil
@vindex nnfolder-nov-is-evil
If non-@code{nil}, this back end will ignore any @acronym{NOV} files.  The
default is @code{nil}.

@item nnfolder-nov-file-suffix
@vindex nnfolder-nov-file-suffix
The extension for @acronym{NOV} files.  The default is @file{.nov}.

@item nnfolder-nov-directory
@vindex nnfolder-nov-directory
The directory where the @acronym{NOV} files should be stored.  If
@code{nil}, @code{nnfolder-directory} is used.

@end table


@findex nnfolder-generate-active-file
@kindex M-x nnfolder-generate-active-file
If you have lots of @code{nnfolder}-like files you'd like to read with
@code{nnfolder}, you can use the @kbd{M-x nnfolder-generate-active-file}
command to make @code{nnfolder} aware of all likely files in
@code{nnfolder-directory}.  This only works if you use long file names,
though.

@node Comparing Mail Back Ends
@subsubsection Comparing Mail Back Ends

First, just for terminology, the @dfn{back end} is the common word for a
low-level access method---a transport, if you will, by which something
is acquired.  The sense is that one's mail has to come from somewhere,
and so selection of a suitable back end is required in order to get that
mail within spitting distance of Gnus.

The same concept exists for Usenet itself: Though access to articles is
typically done by @acronym{NNTP} these days, once upon a midnight dreary, everyone
in the world got at Usenet by running a reader on the machine where the
articles lay (the machine which today we call an @acronym{NNTP} server), and
access was by the reader stepping into the articles' directory spool
area directly.  One can still select between either the @code{nntp} or
@code{nnspool} back ends, to select between these methods, if one happens
actually to live on the server (or can see its spool directly, anyway,
via NFS).

The goal in selecting a mail back end is to pick one which
simultaneously represents a suitable way of dealing with the original
format plus leaving mail in a form that is convenient to use in the
future.  Here are some high and low points on each:

@table @code
@item nnmbox

UNIX systems have historically had a single, very common, and well-defined
format.  All messages arrive in a single @dfn{spool file}, and
they are delineated by a line whose regular expression matches
@samp{^From_}.  (My notational use of @samp{_} is to indicate a space,
to make it clear in this instance that this is not the RFC-specified
@samp{From:} header.)  Because Emacs and therefore Gnus emanate
historically from the Unix environment, it is simplest if one does not
mess a great deal with the original mailbox format, so if one chooses
this back end, Gnus' primary activity in getting mail from the real spool
area to Gnus' preferred directory is simply to copy it, with no
(appreciable) format change in the process.  It is the ``dumbest'' way
to move mail into availability in the Gnus environment.  This makes it
fast to move into place, but slow to parse, when Gnus has to look at
what's where.

@item nnbabyl

Once upon a time, there was the DEC-10 and DEC-20, running operating
systems called TOPS and related things, and the usual (only?) mail
reading environment was a thing called Babyl.  I don't know what format
was used for mail landing on the system, but Babyl had its own internal
format to which mail was converted, primarily involving creating a
spool-file-like entity with a scheme for inserting Babyl-specific
headers and status bits above the top of each message in the file.
Rmail was Emacs's first mail reader, it was written by Richard Stallman,
and Stallman came out of that TOPS/Babyl environment, so he wrote Rmail
to understand the mail files folks already had in existence.  Gnus (and
VM, for that matter) continue to support this format because it's
perceived as having some good qualities in those mailer-specific
headers/status bits stuff.  Rmail itself still exists as well, of
course, and is still maintained within Emacs.  Since Emacs 23, it
uses standard mbox format rather than Babyl.

Both of the above forms leave your mail in a single file on your
file system, and they must parse that entire file each time you take a
look at your mail.

@item nnml

@code{nnml} is the back end which smells the most as though you were
actually operating with an @code{nnspool}-accessed Usenet system.  (In
fact, I believe @code{nnml} actually derived from @code{nnspool} code,
lo these years ago.)  One's mail is taken from the original spool file,
and is then cut up into individual message files, 1:1.  It maintains a
Usenet-style active file (analogous to what one finds in an INN- or
CNews-based news system in (for instance) @file{/var/lib/news/active},
or what is returned via the @samp{NNTP LIST} verb) and also creates
@dfn{overview} files for efficient group entry, as has been defined for
@acronym{NNTP} servers for some years now.  It is slower in mail-splitting,
due to the creation of lots of files, updates to the @code{nnml} active
file, and additions to overview files on a per-message basis, but it is
extremely fast on access because of what amounts to the indexing support
provided by the active file and overviews.

@code{nnml} costs @dfn{inodes} in a big way; that is, it soaks up the
resource which defines available places in the file system to put new
files.  Sysadmins take a dim view of heavy inode occupation within
tight, shared file systems.  But if you live on a personal machine where
the file system is your own and space is not at a premium, @code{nnml}
wins big.

It is also problematic using this back end if you are living in a
FAT16-based Windows world, since much space will be wasted on all these
tiny files.

@item nnmh

The Rand MH mail-reading system has been around UNIX systems for a very
long time; it operates by splitting one's spool file of messages into
individual files, but with little or no indexing support---@code{nnmh}
is considered to be semantically equivalent to ``@code{nnml} without
active file or overviews''.  This is arguably the worst choice, because
one gets the slowness of individual file creation married to the
slowness of access parsing when learning what's new in one's groups.

@item nnfolder

Basically the effect of @code{nnfolder} is @code{nnmbox} (the first
method described above) on a per-group basis.  That is, @code{nnmbox}
itself puts @emph{all} one's mail in one file; @code{nnfolder} provides a
little bit of optimization to this so that each of one's mail groups has
a Unix mail box file.  It's faster than @code{nnmbox} because each group
can be parsed separately, and still provides the simple Unix mail box
format requiring minimal effort in moving the mail around.  In addition,
it maintains an ``active'' file making it much faster for Gnus to figure
out how many messages there are in each separate group.

If you have groups that are expected to have a massive amount of
messages, @code{nnfolder} is not the best choice, but if you receive
only a moderate amount of mail, @code{nnfolder} is probably the most
friendly mail back end all over.

@item nnmaildir

For configuring expiry and other things, @code{nnmaildir} uses
incompatible group parameters, slightly different from those of other
mail back ends.

@code{nnmaildir} is largely similar to @code{nnml}, with some notable
differences. Each message is stored in a separate file, but the
filename is unrelated to the article number in Gnus. @code{nnmaildir}
also stores the equivalent of @code{nnml}'s overview files in one file
per article, so it uses about twice as many inodes as @code{nnml}.
(Use @code{df -i} to see how plentiful your inode supply is.) If this
slows you down or takes up very much space, a non-block-structured
file system.

Since maildirs don't require locking for delivery, the maildirs you use
as groups can also be the maildirs your mail is directly delivered to.
This means you can skip Gnus' mail splitting if your mail is already
organized into different mailboxes during delivery.  A @code{directory}
entry in @code{mail-sources} would have a similar effect, but would
require one set of mailboxes for spooling deliveries (in mbox format,
thus damaging message bodies), and another set to be used as groups (in
whatever format you like).  A maildir has a built-in spool, in the
@code{new/} subdirectory.  Beware that currently, mail moved from
@code{new/} to @code{cur/} instead of via mail splitting will not
undergo treatment such as duplicate checking.

@code{nnmaildir} stores article marks for a given group in the
corresponding maildir, in a way designed so that it's easy to manipulate
them from outside Gnus.  You can tar up a maildir, unpack it somewhere
else, and still have your marks.

@code{nnmaildir} uses a significant amount of memory to speed things up.
(It keeps in memory some of the things that @code{nnml} stores in files
and that @code{nnmh} repeatedly parses out of message files.)  If this
is a problem for you, you can set the @code{nov-cache-size} group
parameter to something small (0 would probably not work, but 1 probably
would) to make it use less memory.  This caching will probably be
removed in the future.

Startup is likely to be slower with @code{nnmaildir} than with other
back ends.  Everything else is likely to be faster, depending in part
on your file system.

@code{nnmaildir} does not use @code{nnoo}, so you cannot use @code{nnoo}
to write an @code{nnmaildir}-derived back end.

@end table


@node Browsing the Web
@section Browsing the Web
@cindex web
@cindex browsing the web
@cindex www
@cindex http

Web-based discussion forums are getting more and more popular.  On many
subjects, the web-based forums have become the most important forums,
eclipsing the importance of mailing lists and news groups.  The reason
is easy to understand---they are friendly to new users; you just point
and click, and there's the discussion.  With mailing lists, you have to
go through a cumbersome subscription procedure, and most people don't
even know what a news group is.

The problem with this scenario is that web browsers are not very good at
being newsreaders.  They do not keep track of what articles you've read;
they do not allow you to score on subjects you're interested in; they do
not allow off-line browsing; they require you to click around and drive
you mad in the end.

So---if web browsers suck at reading discussion forums, why not use Gnus
to do it instead?

Gnus has been getting a bit of a collection of back ends for providing
interfaces to these sources.

@menu
* Archiving Mail::
* Web Searches::                Creating groups from articles that match a string.
* RSS::                         Reading RDF site summary.
* Customizing W3::              Doing stuff to Emacs/W3 from Gnus.
@end menu

All the web sources require Emacs/W3 and the url library or those
alternatives to work.

The main caveat with all these web sources is that they probably won't
work for a very long time.  Gleaning information from the @acronym{HTML} data
is guesswork at best, and when the layout is altered, the Gnus back end
will fail.  If you have reasonably new versions of these back ends,
though, you should be ok.

One thing all these Web methods have in common is that the Web sources
are often down, unavailable or just plain too slow to be fun.  In those
cases, it makes a lot of sense to let the Gnus Agent (@pxref{Gnus
Unplugged}) handle downloading articles, and then you can read them at
leisure from your local disk.  No more World Wide Wait for you.

@node Archiving Mail
@subsection Archiving Mail
@cindex archiving mail
@cindex backup of mail

Some of the back ends, notably @code{nnml}, @code{nnfolder}, and
@code{nnmaildir}, now actually store the article marks with each group.
For these servers, archiving and restoring a group while preserving
marks is fairly simple.

(Preserving the group level and group parameters as well still
requires ritual dancing and sacrifices to the @file{.newsrc.eld} deity
though.)

To archive an entire @code{nnml}, @code{nnfolder}, or @code{nnmaildir}
server, take a recursive copy of the server directory.  There is no need
to shut down Gnus, so archiving may be invoked by @code{cron} or
similar.  You restore the data by restoring the directory tree, and
adding a server definition pointing to that directory in Gnus.  The
@ref{Article Backlog}, @ref{Asynchronous Fetching} and other things
might interfere with overwriting data, so you may want to shut down Gnus
before you restore the data.

@node Web Searches
@subsection Web Searches
@cindex nnweb
@cindex Google
@cindex dejanews
@cindex gmane
@cindex Usenet searches
@cindex searching the Usenet

It's, like, too neat to search the Usenet for articles that match a
string, but it, like, totally @emph{sucks}, like, totally, to use one of
those, like, Web browsers, and you, like, have to, rilly, like, look at
the commercials, so, like, with Gnus you can do @emph{rad}, rilly,
searches without having to use a browser.

The @code{nnweb} back end allows an easy interface to the mighty search
engine.  You create an @code{nnweb} group, enter a search pattern, and
then enter the group and read the articles like you would any normal
group.  The @kbd{G w} command in the group buffer (@pxref{Foreign
Groups}) will do this in an easy-to-use fashion.

@code{nnweb} groups don't really lend themselves to being solid
groups---they have a very fleeting idea of article numbers.  In fact,
each time you enter an @code{nnweb} group (not even changing the search
pattern), you are likely to get the articles ordered in a different
manner.  Not even using duplicate suppression (@pxref{Duplicate
Suppression}) will help, since @code{nnweb} doesn't even know the
@code{Message-ID} of the articles before reading them using some search
engines (Google, for instance).  The only possible way to keep track
of which articles you've read is by scoring on the @code{Date}
header---mark all articles posted before the last date you read the
group as read.

If the search engine changes its output substantially, @code{nnweb}
won't be able to parse it and will fail.  One could hardly fault the Web
providers if they were to do this---their @emph{raison d'@^etre} is to
make money off of advertisements, not to provide services to the
community.  Since @code{nnweb} washes the ads off all the articles, one
might think that the providers might be somewhat miffed.  We'll see.

You must have the @code{url} and @code{W3} package or those alternatives
(try @code{customize-group} on the @samp{mm-url} variable group)
installed to be able to use @code{nnweb}.

Virtual server variables:

@table @code
@item nnweb-type
@vindex nnweb-type
What search engine type is being used.  The currently supported types
are @code{google}, @code{dejanews}, and @code{gmane}.  Note that
@code{dejanews} is an alias to @code{google}.

@item nnweb-search
@vindex nnweb-search
The search string to feed to the search engine.

@item nnweb-max-hits
@vindex nnweb-max-hits
Advisory maximum number of hits per search to display.  The default is
999.

@item nnweb-type-definition
@vindex nnweb-type-definition
Type-to-definition alist.  This alist says what @code{nnweb} should do
with the various search engine types.  The following elements must be
present:

@table @code
@item article
Function to decode the article and provide something that Gnus
understands.

@item map
Function to create an article number to message header and URL alist.

@item search
Function to send the search string to the search engine.

@item address
The address the aforementioned function should send the search string
to.

@item id
Format string URL to fetch an article by @code{Message-ID}.
@end table

@end table


@node RSS
@subsection RSS
@cindex nnrss
@cindex RSS

Some web sites have an RDF Site Summary (@acronym{RSS}).
@acronym{RSS} is a format for summarizing headlines from news related
sites (such as BBC or CNN).  But basically anything list-like can be
presented as an @acronym{RSS} feed: weblogs, changelogs or recent
changes to a wiki (e.g., @url{http://cliki.net/site/recent-changes}).

@acronym{RSS} has a quite regular and nice interface, and it's
possible to get the information Gnus needs to keep groups updated.

Note: you had better use Emacs which supports the @code{utf-8} coding
system because @acronym{RSS} uses UTF-8 for encoding non-@acronym{ASCII}
text by default.  It is also used by default for non-@acronym{ASCII}
group names.

@kindex G R (Group)
Use @kbd{G R} from the group buffer to subscribe to a feed---you will be
prompted for the location, the title and the description of the feed.
The title, which allows any characters, will be used for the group name
and the name of the group data file.  The description can be omitted.

An easy way to get started with @code{nnrss} is to say something like
the following in the group buffer: @kbd{B nnrss RET RET y}, then
subscribe to groups.

The @code{nnrss} back end saves the group data file in
@code{nnrss-directory} (see below) for each @code{nnrss} group.  File
names containing non-@acronym{ASCII} characters will be encoded by the
coding system specified with the @code{nnmail-pathname-coding-system}
variable or other.  Also @xref{Non-ASCII Group Names}, for more
information.

The @code{nnrss} back end generates @samp{multipart/alternative}
@acronym{MIME} articles in which each contains a @samp{text/plain} part
and a @samp{text/html} part.

@cindex OPML
You can also use the following commands to import and export your
subscriptions from a file in @acronym{OPML} format (Outline Processor
Markup Language).

@defun nnrss-opml-import file
Prompt for an @acronym{OPML} file, and subscribe to each feed in the
file.
@end defun

@defun nnrss-opml-export
Write your current @acronym{RSS} subscriptions to a buffer in
@acronym{OPML} format.
@end defun

The following @code{nnrss} variables can be altered:

@table @code
@item nnrss-directory
@vindex nnrss-directory
The directory where @code{nnrss} stores its files.  The default is
@file{~/News/rss/}.

@item nnrss-file-coding-system
@vindex nnrss-file-coding-system
The coding system used when reading and writing the @code{nnrss} groups
data files.  The default is the value of
@code{mm-universal-coding-system} (which defaults to @code{emacs-mule}
in Emacs or @code{escape-quoted} in XEmacs).

@item nnrss-ignore-article-fields
@vindex nnrss-ignore-article-fields
Some feeds update constantly article fields during their publications,
e.g., to indicate the number of comments.  However, if there is
a difference between the local article and the distant one, the latter
is considered to be new.  To avoid this and discard some fields, set this
variable to the list of fields to be ignored.  The default is
@code{'(slash:comments)}.

@item nnrss-use-local
@vindex nnrss-use-local
@findex nnrss-generate-download-script
If you set @code{nnrss-use-local} to @code{t}, @code{nnrss} will read
the feeds from local files in @code{nnrss-directory}.  You can use
the command @code{nnrss-generate-download-script} to generate a
download script using @command{wget}.
@end table

The following code may be helpful, if you want to show the description in
the summary buffer.

@lisp
(add-to-list 'nnmail-extra-headers nnrss-description-field)
(setq gnus-summary-line-format "%U%R%z%I%(%[%4L: %-15,15f%]%) %s%uX\n")

(defun gnus-user-format-function-X (header)
  (let ((descr
         (assq nnrss-description-field (mail-header-extra header))))
    (if descr (concat "\n\t" (cdr descr)) "")))
@end lisp

The following code may be useful to open an nnrss url directly from the
summary buffer.

@lisp
(require 'browse-url)

(defun browse-nnrss-url (arg)
  (interactive "p")
  (let ((url (assq nnrss-url-field
                   (mail-header-extra
                    (gnus-data-header
                     (assq (gnus-summary-article-number)
                           gnus-newsgroup-data))))))
    (if url
        (progn
          (browse-url (cdr url))
          (gnus-summary-mark-as-read-forward 1))
      (gnus-summary-scroll-up arg))))

(eval-after-load "gnus"
  #'(define-key gnus-summary-mode-map
      (kbd "<RET>") 'browse-nnrss-url))
(add-to-list 'nnmail-extra-headers nnrss-url-field)
@end lisp

Even if you have added @samp{text/html} to the
@code{mm-discouraged-alternatives} variable (@pxref{Display
Customization, ,Display Customization, emacs-mime, The Emacs MIME
Manual}) since you don't want to see @acronym{HTML} parts, it might be
more useful especially in @code{nnrss} groups to display
@samp{text/html} parts.  Here's an example of setting
@code{mm-discouraged-alternatives} as a group parameter (@pxref{Group
Parameters}) in order to display @samp{text/html} parts only in
@code{nnrss} groups:

@lisp
;; @r{Set the default value of @code{mm-discouraged-alternatives}.}
(eval-after-load "gnus-sum"
  '(add-to-list
    'gnus-newsgroup-variables
    '(mm-discouraged-alternatives
      . '("text/html" "image/.*"))))

;; @r{Display @samp{text/html} parts in @code{nnrss} groups.}
(add-to-list
 'gnus-parameters
 '("\\`nnrss:" (mm-discouraged-alternatives nil)))
@end lisp


@node Customizing W3
@subsection Customizing W3
@cindex W3
@cindex html
@cindex url
@cindex Netscape

Gnus uses the url library to fetch web pages and Emacs/W3 (or those
alternatives) to display web pages.  Emacs/W3 is documented in its own
manual, but there are some things that may be more relevant for Gnus
users.

For instance, a common question is how to make Emacs/W3 follow links
using the @code{browse-url} functions (which will call some external web
browser like Netscape).  Here's one way:

@lisp
(eval-after-load "w3"
  '(progn
    (fset 'w3-fetch-orig (symbol-function 'w3-fetch))
    (defun w3-fetch (&optional url target)
      (interactive (list (w3-read-url-with-default)))
      (if (eq major-mode 'gnus-article-mode)
          (browse-url url)
        (w3-fetch-orig url target)))))
@end lisp

Put that in your @file{.emacs} file, and hitting links in W3-rendered
@acronym{HTML} in the Gnus article buffers will use @code{browse-url} to
follow the link.


@node Other Sources
@section Other Sources

Gnus can do more than just read news or mail.  The methods described
below allow Gnus to view directories and files as if they were
newsgroups.

@menu
* Directory Groups::            You can read a directory as if it was a newsgroup.
* Anything Groups::             Dired?  Who needs dired?
* Document Groups::             Single files can be the basis of a group.
* Mail-To-News Gateways::       Posting articles via mail-to-news gateways.
* The Empty Backend::           The backend that never has any news.
@end menu


@node Directory Groups
@subsection Directory Groups
@cindex nndir
@cindex directory groups

If you have a directory that has lots of articles in separate files in
it, you might treat it as a newsgroup.  The files have to have numerical
names, of course.

This might be an opportune moment to mention @code{ange-ftp} (and its
successor @code{efs}), that most wonderful of all wonderful Emacs
packages.  When I wrote @code{nndir}, I didn't think much about it---a
back end to read directories.  Big deal.

@code{ange-ftp} changes that picture dramatically.  For instance, if you
enter the @code{ange-ftp} file name
@file{/ftp.hpc.uh.edu:/pub/emacs/ding-list/} as the directory name,
@code{ange-ftp} or @code{efs} will actually allow you to read this
directory over at @samp{sina} as a newsgroup.  Distributed news ahoy!

@code{nndir} will use @acronym{NOV} files if they are present.

@code{nndir} is a ``read-only'' back end---you can't delete or expire
articles with this method.  You can use @code{nnmh} or @code{nnml} for
whatever you use @code{nndir} for, so you could switch to any of those
methods if you feel the need to have a non-read-only @code{nndir}.


@node Anything Groups
@subsection Anything Groups
@cindex nneething

From the @code{nndir} back end (which reads a single spool-like
directory), it's just a hop and a skip to @code{nneething}, which
pretends that any arbitrary directory is a newsgroup.  Strange, but
true.

When @code{nneething} is presented with a directory, it will scan this
directory and assign article numbers to each file.  When you enter such
a group, @code{nneething} must create ``headers'' that Gnus can use.
After all, Gnus is a newsreader, in case you're forgetting.
@code{nneething} does this in a two-step process.  First, it snoops each
file in question.  If the file looks like an article (i.e., the first
few lines look like headers), it will use this as the head.  If this is
just some arbitrary file without a head (e.g., a C source file),
@code{nneething} will cobble up a header out of thin air.  It will use
file ownership, name and date and do whatever it can with these
elements.

All this should happen automatically for you, and you will be presented
with something that looks very much like a newsgroup.  Totally like a
newsgroup, to be precise.  If you select an article, it will be displayed
in the article buffer, just as usual.

If you select a line that represents a directory, Gnus will pop you into
a new summary buffer for this @code{nneething} group.  And so on.  You can
traverse the entire disk this way, if you feel like, but remember that
Gnus is not dired, really, and does not intend to be, either.

There are two overall modes to this action---ephemeral or solid.  When
doing the ephemeral thing (i.e., @kbd{G D} from the group buffer), Gnus
will not store information on what files you have read, and what files
are new, and so on.  If you create a solid @code{nneething} group the
normal way with @kbd{G m}, Gnus will store a mapping table between
article numbers and file names, and you can treat this group like any
other groups.  When you activate a solid @code{nneething} group, you will
be told how many unread articles it contains, etc., etc.

Some variables:

@table @code
@item nneething-map-file-directory
@vindex nneething-map-file-directory
All the mapping files for solid @code{nneething} groups will be stored
in this directory, which defaults to @file{~/.nneething/}.

@item nneething-exclude-files
@vindex nneething-exclude-files
All files that match this regexp will be ignored.  Nice to use to exclude
auto-save files and the like, which is what it does by default.

@item nneething-include-files
@vindex nneething-include-files
Regexp saying what files to include in the group.  If this variable is
non-@code{nil}, only files matching this regexp will be included.

@item nneething-map-file
@vindex nneething-map-file
Name of the map files.
@end table


@node Document Groups
@subsection Document Groups
@cindex nndoc
@cindex documentation group
@cindex help group

@code{nndoc} is a cute little thing that will let you read a single file
as a newsgroup.  Several files types are supported:

@table @code
@cindex Babyl
@item babyl
The Babyl format.

@cindex mbox
@cindex Unix mbox
@item mbox
The standard Unix mbox file.

@cindex MMDF mail box
@item mmdf
The MMDF mail box format.

@item news
Several news articles appended into a file.

@cindex rnews batch files
@item rnews
The rnews batch transport format.

@item nsmail
Netscape mail boxes.

@item mime-parts
@acronym{MIME} multipart messages.

@item standard-digest
The standard (RFC 1153) digest format.

@item mime-digest
A @acronym{MIME} digest of messages.

@item lanl-gov-announce
Announcement messages from LANL Gov Announce.

@cindex git commit messages
@item git
@code{git} commit messages.

@cindex forwarded messages
@item rfc822-forward
A message forwarded according to RFC822.

@item outlook
The Outlook mail box.

@item oe-dbx
The Outlook Express dbx mail box.

@item exim-bounce
A bounce message from the Exim MTA.

@item forward
A message forwarded according to informal rules.

@item rfc934
An RFC934-forwarded message.

@item mailman
A mailman digest.

@item clari-briefs
A digest of Clarinet brief news items.

@item slack-digest
Non-standard digest format---matches most things, but does it badly.

@item mail-in-mail
The last resort.
@end table

You can also use the special ``file type'' @code{guess}, which means
that @code{nndoc} will try to guess what file type it is looking at.
@code{digest} means that @code{nndoc} should guess what digest type the
file is.

@code{nndoc} will not try to change the file or insert any extra headers into
it---it will simply, like, let you use the file as the basis for a
group.  And that's it.

If you have some old archived articles that you want to insert into your
new & spiffy Gnus mail back end, @code{nndoc} can probably help you with
that.  Say you have an old @file{RMAIL} file with mail that you now want
to split into your new @code{nnml} groups.  You look at that file using
@code{nndoc} (using the @kbd{G f} command in the group buffer
(@pxref{Foreign Groups})), set the process mark on all the articles in
the buffer (@kbd{M P b}, for instance), and then re-spool (@kbd{B r})
using @code{nnml}.  If all goes well, all the mail in the @file{RMAIL}
file is now also stored in lots of @code{nnml} directories, and you can
delete that pesky @file{RMAIL} file.  If you have the guts!

Virtual server variables:

@table @code
@item nndoc-article-type
@vindex nndoc-article-type
This should be one of @code{mbox}, @code{babyl}, @code{digest},
@code{news}, @code{rnews}, @code{mmdf}, @code{forward}, @code{rfc934},
@code{rfc822-forward}, @code{mime-parts}, @code{standard-digest},
@code{slack-digest}, @code{clari-briefs}, @code{nsmail}, @code{outlook},
@code{oe-dbx}, @code{mailman}, and @code{mail-in-mail} or @code{guess}.

@item nndoc-post-type
@vindex nndoc-post-type
This variable says whether Gnus is to consider the group a news group or
a mail group.  There are two valid values:  @code{mail} (the default)
and @code{news}.
@end table

@menu
* Document Server Internals::   How to add your own document types.
@end menu


@node Document Server Internals
@subsubsection Document Server Internals

Adding new document types to be recognized by @code{nndoc} isn't
difficult.  You just have to whip up a definition of what the document
looks like, write a predicate function to recognize that document type,
and then hook into @code{nndoc}.

First, here's an example document type definition:

@example
(mmdf
 (article-begin .  "^\^A\^A\^A\^A\n")
 (body-end .  "^\^A\^A\^A\^A\n"))
@end example

The definition is simply a unique @dfn{name} followed by a series of
regexp pseudo-variable settings.  Below are the possible
variables---don't be daunted by the number of variables; most document
types can be defined with very few settings:

@table @code
@item first-article
If present, @code{nndoc} will skip past all text until it finds
something that match this regexp.  All text before this will be
totally ignored.

@item article-begin
This setting has to be present in all document type definitions.  It
says what the beginning of each article looks like.  To do more
complicated things that cannot be dealt with a simple regexp, you can
use @code{article-begin-function} instead of this.

@item article-begin-function
If present, this should be a function that moves point to the beginning
of each article.  This setting overrides @code{article-begin}.

@item head-begin
If present, this should be a regexp that matches the head of the
article.  To do more complicated things that cannot be dealt with a
simple regexp, you can use @code{head-begin-function} instead of this.

@item head-begin-function
If present, this should be a function that moves point to the head of
the article.  This setting overrides @code{head-begin}.

@item head-end
This should match the end of the head of the article.  It defaults to
@samp{^$}---the empty line.

@item body-begin
This should match the beginning of the body of the article.  It defaults
to @samp{^\n}.  To do more complicated things that cannot be dealt with
a simple regexp, you can use @code{body-begin-function} instead of this.

@item body-begin-function
If present, this function should move point to the beginning of the body
of the article.  This setting overrides @code{body-begin}.

@item body-end
If present, this should match the end of the body of the article.  To do
more complicated things that cannot be dealt with a simple regexp, you
can use @code{body-end-function} instead of this.

@item body-end-function
If present, this function should move point to the end of the body of
the article.  This setting overrides @code{body-end}.

@item file-begin
If present, this should match the beginning of the file.  All text
before this regexp will be totally ignored.

@item file-end
If present, this should match the end of the file.  All text after this
regexp will be totally ignored.

@end table

So, using these variables @code{nndoc} is able to dissect a document
file into a series of articles, each with a head and a body.  However, a
few more variables are needed since not all document types are all that
news-like---variables needed to transform the head or the body into
something that's palatable for Gnus:

@table @code
@item prepare-body-function
If present, this function will be called when requesting an article.  It
will be called with point at the start of the body, and is useful if the
document has encoded some parts of its contents.

@item article-transform-function
If present, this function is called when requesting an article.  It's
meant to be used for more wide-ranging transformation of both head and
body of the article.

@item generate-head-function
If present, this function is called to generate a head that Gnus can
understand.  It is called with the article number as a parameter, and is
expected to generate a nice head for the article in question.  It is
called when requesting the headers of all articles.

@item generate-article-function
If present, this function is called to generate an entire article that
Gnus can understand.  It is called with the article number as a
parameter when requesting all articles.

@item dissection-function
If present, this function is called to dissect a document by itself,
overriding @code{first-article}, @code{article-begin},
@code{article-begin-function}, @code{head-begin},
@code{head-begin-function}, @code{head-end}, @code{body-begin},
@code{body-begin-function}, @code{body-end}, @code{body-end-function},
@code{file-begin}, and @code{file-end}.

@end table

Let's look at the most complicated example I can come up with---standard
digests:

@example
(standard-digest
 (first-article . ,(concat "^" (make-string 70 ?-) "\n\n+"))
 (article-begin . ,(concat "\n\n" (make-string 30 ?-) "\n\n+"))
 (prepare-body-function . nndoc-unquote-dashes)
 (body-end-function . nndoc-digest-body-end)
 (head-end . "^ ?$")
 (body-begin . "^ ?\n")
 (file-end . "^End of .*digest.*[0-9].*\n\\*\\*\\|^End of.*Digest *$")
 (subtype digest guess))
@end example

We see that all text before a 70-width line of dashes is ignored; all
text after a line that starts with that @samp{^End of} is also ignored;
each article begins with a 30-width line of dashes; the line separating
the head from the body may contain a single space; and that the body is
run through @code{nndoc-unquote-dashes} before being delivered.

To hook your own document definition into @code{nndoc}, use the
@code{nndoc-add-type} function.  It takes two parameters---the first
is the definition itself and the second (optional) parameter says
where in the document type definition alist to put this definition.
The alist is traversed sequentially, and
@code{nndoc-@var{type}-type-p} is called for a given type @var{type}.
So @code{nndoc-mmdf-type-p} is called to see whether a document is of
@code{mmdf} type, and so on.  These type predicates should return
@code{nil} if the document is not of the correct type; @code{t} if it
is of the correct type; and a number if the document might be of the
correct type.  A high number means high probability; a low number
means low probability with @samp{0} being the lowest valid number.


@node Mail-To-News Gateways
@subsection Mail-To-News Gateways
@cindex mail-to-news gateways
@cindex gateways

If your local @code{nntp} server doesn't allow posting, for some reason
or other, you can post using one of the numerous mail-to-news gateways.
The @code{nngateway} back end provides the interface.

Note that you can't read anything from this back end---it can only be
used to post with.

Server variables:

@table @code
@item nngateway-address
@vindex nngateway-address
This is the address of the mail-to-news gateway.

@item nngateway-header-transformation
@vindex nngateway-header-transformation
News headers often have to be transformed in some odd way or other
for the mail-to-news gateway to accept it.  This variable says what
transformation should be called, and defaults to
@code{nngateway-simple-header-transformation}.  The function is called
narrowed to the headers to be transformed and with one parameter---the
gateway address.

This default function just inserts a new @code{To} header based on the
@code{Newsgroups} header and the gateway address.
For instance, an article with this @code{Newsgroups} header:

@example
Newsgroups: alt.religion.emacs
@end example

will get this @code{To} header inserted:

@example
To: alt-religion-emacs@@GATEWAY
@end example

The following pre-defined functions exist:

@findex nngateway-simple-header-transformation
@table @code

@item nngateway-simple-header-transformation
Creates a @code{To} header that looks like
@var{newsgroup}@@@code{nngateway-address}.

@findex nngateway-mail2news-header-transformation

@item nngateway-mail2news-header-transformation
Creates a @code{To} header that looks like
@code{nngateway-address}.
@end table

@end table

Here's an example:

@lisp
(setq gnus-post-method
      '(nngateway
        "mail2news@@replay.com"
        (nngateway-header-transformation
         nngateway-mail2news-header-transformation)))
@end lisp

So, to use this, simply say something like:

@lisp
(setq gnus-post-method '(nngateway "GATEWAY.ADDRESS"))
@end lisp


@node The Empty Backend
@subsection The Empty Backend
@cindex nnnil

@code{nnnil} is a backend that can be used as a placeholder if you
have to specify a backend somewhere, but don't really want to.  The
classical example is if you don't want to have a primary select
methods, but want to only use secondary ones:

@lisp
(setq gnus-select-method '(nnnil ""))
(setq gnus-secondary-select-methods
      '((nnimap "foo")
        (nnml "")))
@end lisp


@node Combined Groups
@section Combined Groups

Gnus allows combining a mixture of all the other group types into bigger
groups.

@menu
* Virtual Groups::              Combining articles from many groups.
@end menu


@node Virtual Groups
@subsection Virtual Groups
@cindex nnvirtual
@cindex virtual groups
@cindex merging groups

An @dfn{nnvirtual group} is really nothing more than a collection of
other groups.

For instance, if you are tired of reading many small groups, you can
put them all in one big group, and then grow tired of reading one
big, unwieldy group.  The joys of computing!

You specify @code{nnvirtual} as the method.  The address should be a
regexp to match component groups.

All marks in the virtual group will stick to the articles in the
component groups.  So if you tick an article in a virtual group, the
article will also be ticked in the component group from whence it
came.  (And vice versa---marks from the component groups will also be
shown in the virtual group.).  To create an empty virtual group, run
@kbd{G V} (@code{gnus-group-make-empty-virtual}) in the group buffer
and edit the method regexp with @kbd{M-e}
(@code{gnus-group-edit-group-method})

Here's an example @code{nnvirtual} method that collects all Andrea Dworkin
newsgroups into one, big, happy newsgroup:

@lisp
(nnvirtual "^alt\\.fan\\.andrea-dworkin$\\|^rec\\.dworkin.*")
@end lisp

The component groups can be native or foreign; everything should work
smoothly, but if your computer explodes, it was probably my fault.

Collecting the same group from several servers might actually be a good
idea if users have set the Distribution header to limit distribution.
If you would like to read @samp{soc.motss} both from a server in Japan
and a server in Norway, you could use the following as the group regexp:

@example
"^nntp\\+server\\.jp:soc\\.motss$\\|^nntp\\+server\\.no:soc\\.motss$"
@end example

(Remember, though, that if you're creating the group with @kbd{G m}, you
shouldn't double the backslashes, and you should leave off the quote
characters at the beginning and the end of the string.)

This should work kinda smoothly---all articles from both groups should
end up in this one, and there should be no duplicates.  Threading (and
the rest) will still work as usual, but there might be problems with the
sequence of articles.  Sorting on date might be an option here
(@pxref{Selecting a Group}).

One limitation, however---all groups included in a virtual
group have to be alive (i.e., subscribed or unsubscribed).  Killed or
zombie groups can't be component groups for @code{nnvirtual} groups.

@vindex nnvirtual-always-rescan
If the @code{nnvirtual-always-rescan} variable is non-@code{nil} (which
is the default), @code{nnvirtual} will always scan groups for unread
articles when entering a virtual group.  If this variable is @code{nil}
and you read articles in a component group after the virtual group has
been activated, the read articles from the component group will show up
when you enter the virtual group.  You'll also see this effect if you
have two virtual groups that have a component group in common.  If
that's the case, you should set this variable to @code{t}.  Or you can
just tap @code{M-g} on the virtual group every time before you enter
it---it'll have much the same effect.

@code{nnvirtual} can have both mail and news groups as component groups.
When responding to articles in @code{nnvirtual} groups, @code{nnvirtual}
has to ask the back end of the component group the article comes from
whether it is a news or mail back end.  However, when you do a @kbd{^},
there is typically no sure way for the component back end to know this,
and in that case @code{nnvirtual} tells Gnus that the article came from a
not-news back end.  (Just to be on the safe side.)

@kbd{C-c C-n} in the message buffer will insert the @code{Newsgroups}
line from the article you respond to in these cases.

@code{nnvirtual} groups do not inherit anything but articles and marks
from component groups---group parameters, for instance, are not
inherited.


@node Email Based Diary
@section Email Based Diary
@cindex diary
@cindex email based diary
@cindex calendar

This section describes a special mail back end called @code{nndiary},
and its companion library @code{gnus-diary}.  It is ``special'' in the
sense that it is not meant to be one of the standard alternatives for
reading mail with Gnus.  See @ref{Choosing a Mail Back End} for that.
Instead, it is used to treat @emph{some} of your mails in a special way,
namely, as event reminders.

Here is a typical scenario:

@itemize @bullet
@item
You've got a date with Andy Mc Dowell or Bruce Willis (select according
to your sexual preference) in one month.  You don't want to forget it.
@item
So you send a ``reminder'' message (actually, a diary one) to yourself.
@item
You forget all about it and keep on getting and reading new mail, as usual.
@item
From time to time, as you type `g' in the group buffer and as the date
is getting closer, the message will pop up again to remind you of your
appointment, just as if it were new and unread.
@item
Read your ``new'' messages, this one included, and start dreaming again
of the night you're gonna have.
@item
Once the date is over (you actually fell asleep just after dinner), the
message will be automatically deleted if it is marked as expirable.
@end itemize

The Gnus Diary back end has the ability to handle regular appointments
(that wouldn't ever be deleted) as well as punctual ones, operates as a
real mail back end and is configurable in many ways.  All of this is
explained in the sections below.

@menu
* The NNDiary Back End::        Basic setup and usage.
* The Gnus Diary Library::      Utility toolkit on top of nndiary.
* Sending or Not Sending::      A final note on sending diary messages.
@end menu


@node The NNDiary Back End
@subsection The NNDiary Back End
@cindex nndiary
@cindex the nndiary back end

@code{nndiary} is a back end very similar to @code{nnml} (@pxref{Mail
Spool}).  Actually, it could appear as a mix of @code{nnml} and
@code{nndraft}.  If you know @code{nnml}, you're already familiar with
the message storing scheme of @code{nndiary}: one file per message, one
directory per group.

  Before anything, there is one requirement to be able to run
@code{nndiary} properly: you @emph{must} use the group timestamp feature
of Gnus.  This adds a timestamp to each group's parameters.  @ref{Group
Timestamp} to see how it's done.

@menu
* Diary Messages::              What makes a message valid for nndiary.
* Running NNDiary::             NNDiary has two modes of operation.
* Customizing NNDiary::         Bells and whistles.
@end menu

@node Diary Messages
@subsubsection Diary Messages
@cindex nndiary messages
@cindex nndiary mails

@code{nndiary} messages are just normal ones, except for the mandatory
presence of 7 special headers.  These headers are of the form
@code{X-Diary-<something>}, @code{<something>} being one of
@code{Minute}, @code{Hour}, @code{Dom}, @code{Month}, @code{Year},
@code{Time-Zone} and @code{Dow}.  @code{Dom} means ``Day of Month'', and
@code{dow} means ``Day of Week''.  These headers actually behave like