* Image Enhancements:: Modern versions of Emacs/XEmacs can display images.
* Fuzzy Matching:: What's the big fuzz?
* Thwarting Email Spam:: A how-to on avoiding unsolicited commercial email.
-* Pay Hashcash:: Reduce spam by burning CPU time.
* Various Various:: Things that are really various.
Formatting Variables
* Hard Picons:: The way you should do it. You'll learn something.
* Picon Useless Configuration:: Other variables you can trash/tweak/munge/play with.
+Thwarting Email Spam
+
+* 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.
+
Appendices
* XEmacs:: Requirements for installing under XEmacs.
* Image Enhancements:: Modern versions of Emacs/XEmacs can display images.
* Fuzzy Matching:: What's the big fuzz?
* Thwarting Email Spam:: A how-to on avoiding unsolicited commercial email.
-* Pay Hashcash:: Reduce spam by burning CPU time.
* Various Various:: Things that are really various.
@end menu
This is annoying.
-The way to deal with this is having Gnus split out all spam into a
+@menu
+* 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.
+@end menu
+
+@node Anti-Spam Basics
+@subsection Anti-Spam Basics
+@cindex email spam
+@cindex spam
+@cindex UCE
+@cindex unsolicited commercial email
+
+One way of dealing with spam is having Gnus split out all spam into a
@samp{spam} mail group (@pxref{Splitting Mail}).
First, pick one (1) valid mail address that you can be reached at, and
-@node Pay Hashcash
-@section Pay Hashcash
+@node SpamAssassin
+@subsection SpamAssassin, Vipul's Razor, DCC, etc
+@cindex SpamAssassin
+@cindex Vipul's Razor
+@cindex DCC
+
+The days where the hints in the previous section was sufficient in
+avoiding spam is coming to an end. There are many tools out there
+that claim to reduce the amount of spam you get. This section could
+easily become outdated fast, as new products replace old, but
+fortunately most of these tools seem to have similar interfaces. Even
+though this section will use SpamAssassin as an example, it should be
+easy to adapt it to most other tools.
+
+If the tool you are using is not installed on the mail server, you
+need to invoke it yourself. Ideas on how to use the
+@code{:postscript} mail source parameter (@pxref{Mail Source
+Specifiers}) follows.
+
+@lisp
+(setq mail-sources
+ '((file :prescript "formail -bs spamassassin < /var/mail/%u")
+ (pop :user "jrl"
+ :server "pophost"
+ :postscript "mv %t /tmp/foo; formail -bs spamc < /tmp/foo > %t")))
+@end lisp
+
+Once you managed to process your incoming spool somehow, thus making
+the mail contain e.g. a header indicating it is spam, you are ready to
+filter it out. Using normal split methods (@pxref{Splitting Mail}):
+
+@lisp
+(setq nnmail-split-methods '(("spam" "^X-Spam-Flag: YES")
+ ...))
+@end lisp
+
+Or using fancy split methods (@pxref{Fancy Mail Splitting}):
+
+@lisp
+(setq nnmail-split-methods 'nnmail-split-fancy
+ nnmail-split-fancy '(| ("X-Spam-Flag" "YES" "spam")
+ ...))
+@end lisp
+
+Some people might not like the idea of piping the mail through various
+programs using a @code{:prescript} (if some program is buggy, you
+might lose all mail). If you are one of them, another solution is to
+call the external tools during splitting. Example fancy split method:
+
+@lisp
+(setq nnmail-split-fancy '(| (: kevin-spamassassin)
+ ...))
+(defun kevin-spamassassin ()
+ (save-excursion
+ (let ((buf (or (get-buffer " *nnmail incoming*")
+ (get-buffer " *nnml move*"))))
+ (if (not buf)
+ (progn (message "Oops, cannot find message buffer") nil)
+ (set-buffer buf)
+ (if (eq 1 (call-process-region (point-min) (point-max)
+ "spamc" nil nil nil "-c"))
+ "spam")))))
+@end lisp
+
+That is about it. As some spam is likely to get through anyway, you
+might want to have a nifty function to call when you happen to read
+spam. And here is the nifty function:
+
+@lisp
+ (defun my-gnus-raze-spam ()
+ "Submit SPAM to Vipul's Razor, then mark it as expirable."
+ (interactive)
+ (gnus-summary-show-raw-article)
+ (gnus-summary-save-in-pipe "razor-report -f -d")
+ (gnus-summary-mark-as-expirable 1))
+@end lisp
+
+@node Hashcash
+@subsection Hashcash
@cindex hashcash
-@cindex spam
A novel technique to fight spam is to require senders to do something
costly for each message they send. This has the obvious drawback that
-you cannot rely on that everyone uses this technique, since it is
-optional, but it may be useful in smaller communities.
+you cannot rely on that everyone in the world uses this technique,
+since it is not part of the internet standards, but it may be useful
+in smaller communities.
+
+While the tools in the previous section work well in practice, they
+work only because the tools are constantly maintained and updated as
+new form of spam appears. This means that a small percentage of spam
+will always get through. It also means that somewhere, someone needs
+to read lots of spam to update these tools. Hashcash avoids that, but
+instead requires that everyone you communicate with supports the
+scheme. You can view the two approaches as pragmatic vs dogmatic.
+The approaches have their own advantages and disadvantages, but as
+often in the real world, a combination of them is stronger than either
+one of them separately.
@cindex X-Hashcash
The ``something costly'' is to burn CPU time, more specifically to
projects / gnus / commitdiff