3 @setfilename emacs-mime
4 @settitle Emacs MIME Manual
10 * Emacs MIME: (emacs-mime). The MIME de/composition library.
15 @setchapternewpage odd
19 This file documents the Emacs MIME interface functionality.
21 Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003
22 Free Software Foundation, Inc.
24 Permission is granted to copy, distribute and/or modify this document
25 under the terms of the GNU Free Documentation License, Version 1.1 or
26 any later version published by the Free Software Foundation; with no
27 Invariant Sections, with the Front-Cover texts being ``A GNU
28 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
29 license is included in the section entitled ``GNU Free Documentation
30 License'' in the Emacs manual.
32 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
33 this GNU Manual, like GNU software. Copies published by the Free
34 Software Foundation raise funds for GNU development.''
36 This document is part of a collection distributed under the GNU Free
37 Documentation License. If you want to distribute this document
38 separately from the collection, you can do so by adding a copy of the
39 license to the document, as described in section 6 of the license.
45 @title Emacs MIME Manual
47 @author by Lars Magne Ingebrigtsen
50 @vskip 0pt plus 1filll
51 Copyright @copyright{} 1998, 1999, 2000, 2001, 2002, 2003 Free Software
54 Permission is granted to copy, distribute and/or modify this document
55 under the terms of the GNU Free Documentation License, Version 1.1 or
56 any later version published by the Free Software Foundation; with the
57 Invariant Sections being none, with the Front-Cover texts being ``A GNU
58 Manual'', and with the Back-Cover Texts as in (a) below. A copy of the
59 license is included in the section entitled ``GNU Free Documentation
60 License'' in the Emacs manual.
62 (a) The FSF's Back-Cover Text is: ``You have freedom to copy and modify
63 this GNU Manual, like GNU software. Copies published by the Free
64 Software Foundation raise funds for GNU development.''
66 This document is part of a collection distributed under the GNU Free
67 Documentation License. If you want to distribute this document
68 separately from the collection, you can do so by adding a copy of the
69 license to the document, as described in section 6 of the license.
78 This manual documents the libraries used to compose and display
81 This manual is directed at users who want to modify the behaviour of
82 the @sc{mime} encoding/decoding process or want a more detailed
83 picture of how the Emacs @sc{mime} library works, and people who want
84 to write functions and commands that manipulate @sc{mime} elements.
86 @sc{mime} is short for @dfn{Multipurpose Internet Mail Extensions}.
87 This standard is documented in a number of RFCs; mainly RFC2045 (Format
88 of Internet Message Bodies), RFC2046 (Media Types), RFC2047 (Message
89 Header Extensions for Non-ASCII Text), RFC2048 (Registration
90 Procedures), RFC2049 (Conformance Criteria and Examples). It is highly
91 recommended that anyone who intends writing @sc{mime}-compliant software
92 read at least RFC2045 and RFC2047.
95 * Decoding and Viewing:: A framework for decoding and viewing.
96 * Composing:: MML; a language for describing @sc{mime} parts.
97 * Interface Functions:: An abstraction over the basic functions.
98 * Basic Functions:: Utility and basic parsing functions.
99 * Standards:: A summary of RFCs and working documents used.
100 * Index:: Function and variable index.
104 @node Decoding and Viewing
105 @chapter Decoding and Viewing
107 This chapter deals with decoding and viewing @sc{mime} messages on a
110 The main idea is to first analyze a @sc{mime} article, and then allow
111 other programs to do things based on the list of @dfn{handles} that are
112 returned as a result of this analysis.
115 * Dissection:: Analyzing a @sc{mime} message.
116 * Non-MIME:: Analyzing a non-@sc{mime} message.
117 * Handles:: Handle manipulations.
118 * Display:: Displaying handles.
119 * Display Customization:: Variables that affect display.
120 * Files and Directories:: Saving and naming attachments.
121 * New Viewers:: How to write your own viewers.
128 The @code{mm-dissect-buffer} is the function responsible for dissecting
129 a @sc{mime} article. If given a multipart message, it will recursively
130 descend the message, following the structure, and return a tree of
131 @sc{mime} handles that describes the structure of the message.
135 @vindex mm-uu-configure-list
137 Gnus also understands some non-@sc{mime} attachments, such as
138 postscript, uuencode, binhex, yenc, shar, forward, gnatsweb, pgp,
139 diff. Each of these features can be disabled by add an item into
140 @code{mm-uu-configure-list}. For example,
144 (add-to-list 'mm-uu-configure-list '(pgp-signed . disabled))
170 Non-@sc{mime} forwarded message.
178 PGP signed clear text.
181 @findex pgp-encrypted
182 PGP encrypted clear text.
189 @findex emacs-sources
190 @vindex mm-uu-emacs-sources-regexp
191 Emacs source code. This item works only in the groups matching
192 @code{mm-uu-emacs-sources-regexp}.
196 @vindex mm-uu-diff-groups-regexp
197 Patches. This is intended for groups where diffs of committed files
198 are automatically sent to. It only works in groups matching
199 @code{mm-uu-diff-groups-regexp}.
206 A @sc{mime} handle is a list that fully describes a @sc{mime}
209 The following macros can be used to access elements in a handle:
212 @item mm-handle-buffer
213 @findex mm-handle-buffer
214 Return the buffer that holds the contents of the undecoded @sc{mime}
218 @findex mm-handle-type
219 Return the parsed @code{Content-Type} of the part.
221 @item mm-handle-encoding
222 @findex mm-handle-encoding
223 Return the @code{Content-Transfer-Encoding} of the part.
225 @item mm-handle-undisplayer
226 @findex mm-handle-undisplayer
227 Return the object that can be used to remove the displayed part (if it
230 @item mm-handle-set-undisplayer
231 @findex mm-handle-set-undisplayer
232 Set the undisplayer object.
234 @item mm-handle-disposition
235 @findex mm-handle-disposition
236 Return the parsed @code{Content-Disposition} of the part.
238 @item mm-handle-disposition
239 @findex mm-handle-disposition
240 Return the description of the part.
242 @item mm-get-content-id
243 Returns the handle(s) referred to by @code{Content-ID}.
251 Functions for displaying, removing and saving.
254 @item mm-display-part
255 @findex mm-display-part
259 @findex mm-remove-part
260 Remove the part (if it has been displayed).
263 @findex mm-inlinable-p
264 Say whether a @sc{mime} type can be displayed inline.
266 @item mm-automatic-display-p
267 @findex mm-automatic-display-p
268 Say whether a @sc{mime} type should be displayed automatically.
270 @item mm-destroy-part
271 @findex mm-destroy-part
272 Free all resources occupied by a part.
276 Offer to save the part in a file.
280 Offer to pipe the part to some process.
282 @item mm-interactively-view-part
283 @findex mm-interactively-view-part
284 Prompt for a mailcap method to use to view the part.
289 @node Display Customization
290 @section Display Customization
294 @item mm-inline-media-tests
295 @vindex mm-inline-media-tests
296 This is an alist where the key is a @sc{mime} type, the second element
297 is a function to display the part @dfn{inline} (i.e., inside Emacs), and
298 the third element is a form to be @code{eval}ed to say whether the part
299 can be displayed inline.
301 This variable specifies whether a part @emph{can} be displayed inline,
302 and, if so, how to do it. It does not say whether parts are
303 @emph{actually} displayed inline.
305 @item mm-inlined-types
306 @vindex mm-inlined-types
307 This, on the other hand, says what types are to be displayed inline, if
308 they satisfy the conditions set by the variable above. It's a list of
309 @sc{mime} media types.
311 @item mm-automatic-display
312 @vindex mm-automatic-display
313 This is a list of types that are to be displayed ``automatically'', but
314 only if the above variable allows it. That is, only inlinable parts can
315 be displayed automatically.
317 @item mm-automatic-external-display
318 @vindex mm-automatic-external-display
319 This is a list of types that will be displayed automatically in an
322 @item mm-keep-viewer-alive-types
323 @vindex mm-keep-viewer-alive-types
324 This is a list of media types for which the external viewer will not
325 be killed when selecting a different article.
327 @item mm-attachment-override-types
328 @vindex mm-attachment-override-types
329 Some @sc{mime} agents create parts that have a content-disposition of
330 @samp{attachment}. This variable allows overriding that disposition and
331 displaying the part inline. (Note that the disposition is only
332 overridden if we are able to, and want to, display the part inline.)
334 @item mm-discouraged-alternatives
335 @vindex mm-discouraged-alternatives
336 List of @sc{mime} types that are discouraged when viewing
337 @samp{multipart/alternative}. Viewing agents are supposed to view the
338 last possible part of a message, as that is supposed to be the richest.
339 However, users may prefer other types instead, and this list says what
340 types are most unwanted. If, for instance, @samp{text/html} parts are
341 very unwanted, and @samp{text/richtext} parts are somewhat unwanted,
342 you could say something like:
345 (setq mm-discouraged-alternatives
346 '("text/html" "text/richtext")
348 (remove "text/html" mm-automatic-display))
351 @item mm-inline-large-images
352 @vindex mm-inline-large-images
353 When displaying inline images that are larger than the window, XEmacs
354 does not enable scrolling, which means that you cannot see the whole
355 image. To prevent this, the library tries to determine the image size
356 before displaying it inline, and if it doesn't fit the window, the
357 library will display it externally (e.g. with @samp{ImageMagick} or
358 @samp{xv}). Setting this variable to @code{t} disables this check and
359 makes the library display all inline images as inline, regardless of
362 @item mm-inline-override-types
363 @vindex mm-inline-override-types
364 @code{mm-inlined-types} may include regular expressions, for example to
365 specify that all @samp{text/.*} parts be displayed inline. If a user
366 prefers to have a type that matches such a regular expression be treated
367 as an attachment, that can be accomplished by setting this variable to a
368 list containing that type. For example assuming @code{mm-inlined-types}
369 includes @samp{text/.*}, then including @samp{text/html} in this
370 variable will cause @samp{text/html} parts to be treated as attachments.
372 @item mm-text-html-renderer
373 @vindex mm-text-html-renderer
374 This selects the function used to render @sc{html}. The predefined
375 renderers are selected by the symbols @code{w3},
376 @code{w3m}@footnote{See @uref{http://emacs-w3m.namazu.org/} for more
377 information about emacs-w3m}, @code{links}, @code{lynx},
378 @code{w3m-standalone} or @code{html2text}. If @code{nil} use an
379 external viewer. You can also specify a function, which will be
380 called with a @sc{mime} handle as the argument.
382 @item mm-inline-text-html-with-images
383 @vindex mm-inline-text-html-with-images
384 Some @sc{html} mails might have the trick of spammers using
385 @samp{<img>} tags. It is likely to be intended to verify whether you
386 have read the mail. You can prevent your personal informations from
387 leaking by setting this option to @code{nil} (which is the default).
388 It is currently ignored by Emacs/w3. For emacs-w3m, you may use the
389 command @kbd{t} on the image anchor to show an image even if it is
390 @code{nil}.@footnote{The command @kbd{T} will load all images. If you
391 have set the option @code{w3m-key-binding} to @code{info}, use @kbd{i}
394 @item mm-w3m-safe-url-regexp
395 @vindex mm-w3m-safe-url-regexp
396 A regular expression that matches safe URL names, i.e. URLs that are
397 unlikely to leak personal information when rendering @sc{html} email
398 (the default value is @samp{\\`cid:}). If @code{nil} consider all
401 @item mm-inline-text-html-with-w3m-keymap
402 @vindex mm-inline-text-html-with-w3m-keymap
403 You can use emacs-w3m command keys in the inlined text/html part by
404 setting this option to non-@code{nil}. The default value is @code{t}.
406 @item mm-external-terminal-program
407 @vindex mm-external-terminal-program
408 The program used to start an external terminal.
412 @node Files and Directories
413 @section Files and Directories
417 @item mm-default-directory
418 @vindex mm-default-directory
419 The default directory for saving attachments. If @code{nil} use
420 @code{default-directory}.
422 @item mm-tmp-directory
423 @vindex mm-tmp-directory
424 Directory for storing temporary files.
426 @item mm-file-name-rewrite-functions
427 @vindex mm-file-name-rewrite-functions
428 A list of functions used for rewriting file names of @sc{mime}
429 parts. Each function is applied successively to the file name.
430 Ready-made functions include
433 @item mm-file-name-delete-whitespace
434 @findex mm-file-name-delete-whitespace
435 Remove all whitespace.
437 @item mm-file-name-trim-whitespace
438 @findex mm-file-name-trim-whitespace
439 Remove leading and trailing whitespace.
441 @item mm-file-name-collapse-whitespace
442 @findex mm-file-name-collapse-whitespace
443 Collapse multiple whitespace characters.
445 @item mm-file-name-replace-whitespace
446 @findex mm-file-name-replace-whitespace
447 @vindex mm-file-name-replace-whitespace
448 Replace whitespace with underscores. Set the variable
449 @code{mm-file-name-replace-whitespace} to any other string if you do
450 not like underscores.
454 The standard Emacs functions @code{capitalize}, @code{downcase},
455 @code{upcase} and @code{upcase-initials} might also prove useful.
457 @item mm-path-name-rewrite-functions
458 @vindex mm-path-name-rewrite-functions
459 List of functions used for rewriting the full file names of @sc{mime}
460 parts. This is used when viewing parts externally, and is meant for
461 transforming the absolute name so that non-compliant programs can find
462 the file where it's saved.
469 Here's an example viewer for displaying @code{text/enriched} inline:
472 (defun mm-display-enriched-inline (handle)
475 (mm-insert-part handle)
476 (save-window-excursion
477 (enriched-decode (point-min) (point-max))
478 (setq text (buffer-string))))
479 (mm-insert-inline handle text)))
482 We see that the function takes a @sc{mime} handle as its parameter. It
483 then goes to a temporary buffer, inserts the text of the part, does some
484 work on the text, stores the result, goes back to the buffer it was
485 called from and inserts the result.
487 The two important helper functions here are @code{mm-insert-part} and
488 @code{mm-insert-inline}. The first function inserts the text of the
489 handle in the current buffer. It handles charset and/or content
490 transfer decoding. The second function just inserts whatever text you
491 tell it to insert, but it also sets things up so that the text can be
492 ``undisplayed'' in a convenient manner.
498 @cindex MIME Composing
500 @cindex MIME Meta Language
502 Creating a @sc{mime} message is boring and non-trivial. Therefore, a
503 library called @code{mml} has been defined that parses a language called
504 MML (@sc{mime} Meta Language) and generates @sc{mime} messages.
506 @findex mml-generate-mime
507 The main interface function is @code{mml-generate-mime}. It will
508 examine the contents of the current (narrowed-to) buffer and return a
509 string containing the @sc{mime} message.
512 * Simple MML Example:: An example MML document.
513 * MML Definition:: All valid MML elements.
514 * Advanced MML Example:: Another example MML document.
515 * Encoding Customization:: Variables that affect encoding.
516 * Charset Translation:: How charsets are mapped from @sc{mule} to @sc{mime}.
517 * Conversion:: Going from @sc{mime} to MML and vice versa.
518 * Flowed text:: Soft and hard newlines.
522 @node Simple MML Example
523 @section Simple MML Example
525 Here's a simple @samp{multipart/alternative}:
528 <#multipart type=alternative>
529 This is a plain text part.
530 <#part type=text/enriched>
531 <center>This is a centered enriched part</center>
535 After running this through @code{mml-generate-mime}, we get this:
538 Content-Type: multipart/alternative; boundary="=-=-="
544 This is a plain text part.
547 Content-Type: text/enriched
550 <center>This is a centered enriched part</center>
557 @section MML Definition
559 The MML language is very simple. It looks a bit like an SGML
560 application, but it's not.
562 The main concept of MML is the @dfn{part}. Each part can be of a
563 different type or use a different charset. The way to delineate a part
564 is with a @samp{<#part ...>} tag. Multipart parts can be introduced
565 with the @samp{<#multipart ...>} tag. Parts are ended by the
566 @samp{<#/part>} or @samp{<#/multipart>} tags. Parts started with the
567 @samp{<#part ...>} tags are also closed by the next open tag.
569 There's also the @samp{<#external ...>} tag. These introduce
570 @samp{external/message-body} parts.
572 Each tag can contain zero or more parameters on the form
573 @samp{parameter=value}. The values may be enclosed in quotation marks,
574 but that's not necessary unless the value contains white space. So
575 @samp{filename=/home/user/#hello$^yes} is perfectly valid.
577 The following parameters have meaning in MML; parameters that have no
578 meaning are ignored. The MML parameter names are the same as the
579 @sc{mime} parameter names; the things in the parentheses say which
580 header it will be used in.
584 The @sc{mime} type of the part (@code{Content-Type}).
587 Use the contents of the file in the body of the part
588 (@code{Content-Disposition}).
591 The contents of the body of the part are to be encoded in the character
592 set speficied (@code{Content-Type}). @xref{Charset Translation}.
595 Might be used to suggest a file name if the part is to be saved
596 to a file (@code{Content-Type}).
599 Valid values are @samp{inline} and @samp{attachment}
600 (@code{Content-Disposition}).
603 Valid values are @samp{7bit}, @samp{8bit}, @samp{quoted-printable} and
604 @samp{base64} (@code{Content-Transfer-Encoding}). @xref{Charset
608 A description of the part (@code{Content-Description}).
611 RFC822 date when the part was created (@code{Content-Disposition}).
613 @item modification-date
614 RFC822 date when the part was modified (@code{Content-Disposition}).
617 RFC822 date when the part was read (@code{Content-Disposition}).
620 Who to encrypt/sign the part to. This field is used to override any
621 auto-detection based on the To/CC headers.
624 Identity used to sign the part. This field is used to override the
628 The size (in octets) of the part (@code{Content-Disposition}).
631 What technology to sign this MML part with (@code{smime}, @code{pgp}
635 What technology to encrypt this MML part with (@code{smime},
636 @code{pgp} or @code{pgpmime})
640 Parameters for @samp{application/octet-stream}:
644 Type of the part; informal---meant for human readers
645 (@code{Content-Type}).
648 Parameters for @samp{message/external-body}:
652 A word indicating the supported access mechanism by which the file may
653 be obtained. Values include @samp{ftp}, @samp{anon-ftp}, @samp{tftp},
654 @samp{localfile}, and @samp{mailserver}. (@code{Content-Type}.)
657 The RFC822 date after which the file may no longer be fetched.
658 (@code{Content-Type}.)
661 The size (in octets) of the file. (@code{Content-Type}.)
664 Valid values are @samp{read} and @samp{read-write}
665 (@code{Content-Type}).
669 Parameters for @samp{sign=smime}:
674 File containing key and certificate for signer.
678 Parameters for @samp{encrypt=smime}:
683 File containing certificate for recipient.
688 @node Advanced MML Example
689 @section Advanced MML Example
691 Here's a complex multipart message. It's a @samp{multipart/mixed} that
692 contains many parts, one of which is a @samp{multipart/alternative}.
695 <#multipart type=mixed>
696 <#part type=image/jpeg filename=~/rms.jpg disposition=inline>
697 <#multipart type=alternative>
698 This is a plain text part.
699 <#part type=text/enriched name=enriched.txt>
700 <center>This is a centered enriched part</center>
702 This is a new plain text part.
703 <#part disposition=attachment>
704 This plain text part is an attachment.
708 And this is the resulting @sc{mime} message:
711 Content-Type: multipart/mixed; boundary="=-=-="
719 Content-Type: image/jpeg;
721 Content-Disposition: inline;
723 Content-Transfer-Encoding: base64
725 /9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAgGBgcGBQgHBwcJCQgKDBQNDAsLDBkSEw8UHRof
726 Hh0aHBwgJC4nICIsIxwcKDcpLDAxNDQ0Hyc5PTgyPC4zNDL/wAALCAAwADABAREA/8QAHwAA
727 AQUBAQEBAQEAAAAAAAAAAAECAwQFBgcICQoL/8QAtRAAAgEDAwIEAwUFBAQAAAF9AQIDAAQR
728 BRIhMUEGE1FhByJxFDKBkaEII0KxwRVS0fAkM2JyggkKFhcYGRolJicoKSo0NTY3ODk6Q0RF
729 RkdISUpTVFVWV1hZWmNkZWZnaGlqc3R1dnd4eXqDhIWGh4iJipKTlJWWl5iZmqKjpKWmp6ip
730 qrKztLW2t7i5usLDxMXGx8jJytLT1NXW19jZ2uHi4+Tl5ufo6erx8vP09fb3+Pn6/9oACAEB
731 AAA/AO/rifFHjldNuGsrDa0qcSSHkA+gHrXKw+LtWLrMb+RgTyhbr+HSug07xNqV9fQtZrNI
732 AyiaE/NuBPOOOP0rvRNE880KOC8TbXXGCv1FPqjrF4LDR7u5L7SkTFT/ALWOP1xXgTuXfc7E
733 sx6nua6rwp4IvvEM8chCxWxOdzn7wz6V9AaB4S07w9p5itow0rDLSY5Pt9K43xO66P4xs71m
734 2QXiGCbA4yOVJ9+1aYORkdK434lyNH4ahCnG66VT9Nj15JFbPdX0MS43M4VQf5/yr2vSpLnw
735 5ZW8dlCZ8KFXjOPX0/mK6rSPEGt3Angu44fNEReHYNvIH3TzXDeKNO8RX+kSX2ouZkicTIOc
736 L+g7E810ulFjpVtv3bwgB3HJyK5L4quY/C9sVxk3ij/xx6850u7t1mtp/wDlpEw3An3Jr3Dw
737 34gsbWza4nBlhC5LDsaW6+IFgupQyCF3iHH7gA7c9R9ay7zx6t7aX9jHC4smhfBkGCvHGfrm
738 tLQ7hbnRrV1GPkAP1x1/Hr+Ncr8Vzjwrbf8AX6v/AKA9eQRyYlQk8Yx9K6XTNbkgia2ciSIn
739 7p5Ga9Atte0LTLKO6it4i7dVRFJDcZ4PvXN+JvEMF9bILVGXJLSZ4zkjivRPDaeX4b08HOTC
740 pOffmua+KkbS+GLVUGT9tT/0B68eeIpIFYjB70+OOVXyoOM9+M1eaWeCLzHPyHGO/NVWvJJm
741 jQ8KGH1NfQWhXSXmh2c8eArRLwO3HSv/2Q==
744 Content-Type: multipart/alternative; boundary="==-=-="
750 This is a plain text part.
753 Content-Type: text/enriched;
757 <center>This is a centered enriched part</center>
763 This is a new plain text part.
766 Content-Disposition: attachment
769 This plain text part is an attachment.
774 @node Encoding Customization
775 @section Encoding Customization
779 @item mm-body-charset-encoding-alist
780 @vindex mm-body-charset-encoding-alist
781 Mapping from @sc{mime} charset to encoding to use. This variable is
782 usually used except, e.g., when other requirements force a specific
783 encoding (digitally signed messages require 7bit encodings). The
787 ((iso-2022-jp . 7bit)
788 (iso-2022-jp-2 . 7bit)
794 As an example, if you do not want to have ISO-8859-1 characters
795 quoted-printable encoded, you may add @code{(iso-8859-1 . 8bit)} to
796 this variable. You can override this setting on a per-message basis
797 by using the @code{encoding} MML tag (@pxref{MML Definition}).
799 @item mm-coding-system-priorities
800 @vindex mm-coding-system-priorities
801 Prioritize coding systems to use for outgoing messages. The default
802 is @code{nil}, which means to use the defaults in Emacs. It is a list of
803 coding system symbols (aliases of coding systems does not work, use
804 @kbd{M-x describe-coding-system} to make sure you are not specifying
805 an alias in this variable). For example, if you have configured Emacs
806 to use prefer UTF-8, but wish that outgoing messages should be sent in
807 ISO-8859-1 if possible, you can set this variable to
808 @code{(iso-latin-1)}. You can override this setting on a per-message
809 basis by using the @code{charset} MML tag (@pxref{MML Definition}).
811 @item mm-content-transfer-encoding-defaults
812 @vindex mm-content-transfer-encoding-defaults
813 Mapping from @sc{mime} types to encoding to use. This variable is usually
814 used except, e.g., when other requirements force a safer encoding
815 (digitally signed messages require 7bit encoding). Besides the normal
816 @sc{mime} encodings, @code{qp-or-base64} may be used to indicate that for
817 each case the most efficient of quoted-printable and base64 should be
818 used. You can override this setting on a per-message basis by using
819 the @code{encoding} MML tag (@pxref{MML Definition}).
821 @item mm-use-ultra-safe-encoding
822 @vindex mm-use-ultra-safe-encoding
823 When this is non-@code{nil}, it means that textual parts are encoded as
824 quoted-printable if they contain lines longer than 76 characters or
825 starting with "From " in the body. Non-7bit encodings (8bit, binary)
826 are generally disallowed. This reduce the probability that a non-8bit
827 clean MTA or MDA changes the message. This should never be set
828 directly, but bound by other functions when necessary (e.g., when
829 encoding messages that are to be digitally signed).
833 @node Charset Translation
834 @section Charset Translation
837 During translation from MML to @sc{mime}, for each @sc{mime} part which
838 has been composed inside Emacs, an appropriate charset has to be chosen.
840 @vindex mail-parse-charset
841 If you are running a non-@sc{mule} Emacs, this process is simple: If the
842 part contains any non-ASCII (8-bit) characters, the @sc{mime} charset
843 given by @code{mail-parse-charset} (a symbol) is used. (Never set this
844 variable directly, though. If you want to change the default charset,
845 please consult the documentation of the package which you use to process
847 @xref{Various Message Variables, , Various Message Variables, message,
848 Message Manual}, for example.)
849 If there are only ASCII characters, the @sc{mime} charset US-ASCII is
855 @vindex mm-mime-mule-charset-alist
856 Things are slightly more complicated when running Emacs with @sc{mule}
857 support. In this case, a list of the @sc{mule} charsets used in the
858 part is obtained, and the @sc{mule} charsets are translated to @sc{mime}
859 charsets by consulting the variable @code{mm-mime-mule-charset-alist}.
860 If this results in a single @sc{mime} charset, this is used to encode
861 the part. But if the resulting list of @sc{mime} charsets contains more
862 than one element, two things can happen: If it is possible to encode the
863 part via UTF-8, this charset is used. (For this, Emacs must support
864 the @code{utf-8} coding system, and the part must consist entirely of
865 characters which have Unicode counterparts.) If UTF-8 is not available
866 for some reason, the part is split into several ones, so that each one
867 can be encoded with a single @sc{mime} charset. The part can only be
868 split at line boundaries, though---if more than one @sc{mime} charset is
869 required to encode a single line, it is not possible to encode the part.
871 When running Emacs with @sc{mule} support, the preferences for which
872 coding system to use is inherited from Emacs itself. This means that
873 if Emacs is set up to prefer UTF-8, it will be used when encoding
874 messages. You can modify this by altering the
875 @code{mm-coding-system-priorities} variable though (@pxref{Encoding
878 The charset to be used can be overriden by setting the @code{charset}
879 MML tag (@pxref{MML Definition}) when composing the message.
881 The encoding of characters (quoted-printable, 8bit etc) is orthogonal
882 to the discussion here, and is controlled by the variables
883 @code{mm-body-charset-encoding-alist} and
884 @code{mm-content-transfer-encoding-defaults} (@pxref{Encoding
891 A (multipart) @sc{mime} message can be converted to MML with the
892 @code{mime-to-mml} function. It works on the message in the current
893 buffer, and substitutes MML markup for @sc{mime} boundaries.
894 Non-textual parts do not have their contents in the buffer, but instead
895 have the contents in separate buffers that are referred to from the MML
899 An MML message can be converted back to @sc{mime} by the
900 @code{mml-to-mime} function.
902 These functions are in certain senses ``lossy''---you will not get back
903 an identical message if you run @sc{mime-to-mml} and then
904 @sc{mml-to-mime}. Not only will trivial things like the order of the
905 headers differ, but the contents of the headers may also be different.
906 For instance, the original message may use base64 encoding on text,
907 while @sc{mml-to-mime} may decide to use quoted-printable encoding, and
910 In essence, however, these two functions should be the inverse of each
911 other. The resulting contents of the message should remain equivalent,
917 @cindex format=flowed
919 The Emacs @sc{mime} library will respect the @code{use-hard-newlines}
920 variable (@pxref{Hard and Soft Newlines, ,Hard and Soft Newlines,
921 emacs, Emacs Manual}) when encoding a message, and the
922 ``format=flowed'' Content-Type parameter when decoding a message.
924 On encoding text, lines terminated by soft newline characters are
925 filled together and wrapped after the column decided by
926 @code{fill-flowed-encode-column}. This variable controls how the text
927 will look in a client that does not support flowed text, the default
928 is to wrap after 66 characters. If hard newline characters are not
929 present in the buffer, no flow encoding occurs.
931 On decoding flowed text, lines with soft newline characters are filled
932 together and wrapped after the column decided by
933 @code{fill-flowed-display-column}. The default is to wrap after
939 @node Interface Functions
940 @chapter Interface Functions
941 @cindex interface functions
944 The @code{mail-parse} library is an abstraction over the actual
945 low-level libraries that are described in the next chapter.
947 Standards change, and so programs have to change to fit in the new
948 mold. For instance, RFC2045 describes a syntax for the
949 @code{Content-Type} header that only allows ASCII characters in the
950 parameter list. RFC2231 expands on RFC2045 syntax to provide a scheme
951 for continuation headers and non-ASCII characters.
953 The traditional way to deal with this is just to update the library
954 functions to parse the new syntax. However, this is sometimes the wrong
955 thing to do. In some instances it may be vital to be able to understand
956 both the old syntax as well as the new syntax, and if there is only one
957 library, one must choose between the old version of the library and the
958 new version of the library.
960 The Emacs @sc{mime} library takes a different tack. It defines a
961 series of low-level libraries (@file{rfc2047.el}, @file{rfc2231.el}
962 and so on) that parses strictly according to the corresponding
963 standard. However, normal programs would not use the functions
964 provided by these libraries directly, but instead use the functions
965 provided by the @code{mail-parse} library. The functions in this
966 library are just aliases to the corresponding functions in the latest
967 low-level libraries. Using this scheme, programs get a consistent
968 interface they can use, and library developers are free to create
969 write code that handles new standards.
971 The following functions are defined by this library:
974 @item mail-header-parse-content-type
975 @findex mail-header-parse-content-type
976 Parse a @code{Content-Type} header and return a list on the following
981 (attribute1 . value1)
982 (attribute2 . value2)
989 (mail-header-parse-content-type
990 "image/gif; name=\"b980912.gif\"")
991 @result{} ("image/gif" (name . "b980912.gif"))
994 @item mail-header-parse-content-disposition
995 @findex mail-header-parse-content-disposition
996 Parse a @code{Content-Disposition} header and return a list on the same
997 format as the function above.
999 @item mail-content-type-get
1000 @findex mail-content-type-get
1001 Takes two parameters---a list on the format above, and an attribute.
1002 Returns the value of the attribute.
1005 (mail-content-type-get
1006 '("image/gif" (name . "b980912.gif")) 'name)
1007 @result{} "b980912.gif"
1010 @item mail-header-encode-parameter
1011 @findex mail-header-encode-parameter
1012 Takes a parameter string and returns an encoded version of the string.
1013 This is used for parameters in headers like @code{Content-Type} and
1014 @code{Content-Disposition}.
1016 @item mail-header-remove-comments
1017 @findex mail-header-remove-comments
1018 Return a comment-free version of a header.
1021 (mail-header-remove-comments
1022 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1023 @result{} "Gnus/5.070027 "
1026 @item mail-header-remove-whitespace
1027 @findex mail-header-remove-whitespace
1028 Remove linear white space from a header. Space inside quoted strings
1029 and comments is preserved.
1032 (mail-header-remove-whitespace
1033 "image/gif; name=\"Name with spaces\"")
1034 @result{} "image/gif;name=\"Name with spaces\""
1037 @item mail-header-get-comment
1038 @findex mail-header-get-comment
1039 Return the last comment in a header.
1042 (mail-header-get-comment
1043 "Gnus/5.070027 (Pterodactyl Gnus v0.27) (Finnish Landrace)")
1044 @result{} "Finnish Landrace"
1047 @item mail-header-parse-address
1048 @findex mail-header-parse-address
1049 Parse an address and return a list containing the mailbox and the
1053 (mail-header-parse-address
1054 "Hrvoje Niksic <hniksic@@srce.hr>")
1055 @result{} ("hniksic@@srce.hr" . "Hrvoje Niksic")
1058 @item mail-header-parse-addresses
1059 @findex mail-header-parse-addresses
1060 Parse a string with list of addresses and return a list of elements like
1061 the one described above.
1064 (mail-header-parse-addresses
1065 "Hrvoje Niksic <hniksic@@srce.hr>, Steinar Bang <sb@@metis.no>")
1066 @result{} (("hniksic@@srce.hr" . "Hrvoje Niksic")
1067 ("sb@@metis.no" . "Steinar Bang"))
1070 @item mail-header-parse-date
1071 @findex mail-header-parse-date
1072 Parse a date string and return an Emacs time structure.
1074 @item mail-narrow-to-head
1075 @findex mail-narrow-to-head
1076 Narrow the buffer to the header section of the buffer. Point is placed
1077 at the beginning of the narrowed buffer.
1079 @item mail-header-narrow-to-field
1080 @findex mail-header-narrow-to-field
1081 Narrow the buffer to the header under point. Understands continuation
1084 @item mail-header-fold-field
1085 @findex mail-header-fold-field
1086 Fold the header under point.
1088 @item mail-header-unfold-field
1089 @findex mail-header-unfold-field
1090 Unfold the header under point.
1092 @item mail-header-field-value
1093 @findex mail-header-field-value
1094 Return the value of the field under point.
1096 @item mail-encode-encoded-word-region
1097 @findex mail-encode-encoded-word-region
1098 Encode the non-ASCII words in the region. For instance,
1099 @samp{Naïve} is encoded as @samp{=?iso-8859-1?q?Na=EFve?=}.
1101 @item mail-encode-encoded-word-buffer
1102 @findex mail-encode-encoded-word-buffer
1103 Encode the non-ASCII words in the current buffer. This function is
1104 meant to be called narrowed to the headers of a message.
1106 @item mail-encode-encoded-word-string
1107 @findex mail-encode-encoded-word-string
1108 Encode the words that need encoding in a string, and return the result.
1111 (mail-encode-encoded-word-string
1112 "This is naïve, baby")
1113 @result{} "This is =?iso-8859-1?q?na=EFve,?= baby"
1116 @item mail-decode-encoded-word-region
1117 @findex mail-decode-encoded-word-region
1118 Decode the encoded words in the region.
1120 @item mail-decode-encoded-word-string
1121 @findex mail-decode-encoded-word-string
1122 Decode the encoded words in the string and return the result.
1125 (mail-decode-encoded-word-string
1126 "This is =?iso-8859-1?q?na=EFve,?= baby")
1127 @result{} "This is naïve, baby"
1132 Currently, @code{mail-parse} is an abstraction over @code{ietf-drums},
1133 @code{rfc2047}, @code{rfc2045} and @code{rfc2231}. These are documented
1134 in the subsequent sections.
1138 @node Basic Functions
1139 @chapter Basic Functions
1141 This chapter describes the basic, ground-level functions for parsing and
1142 handling. Covered here is parsing @code{From} lines, removing comments
1143 from header lines, decoding encoded words, parsing date headers and so
1144 on. High-level functionality is dealt with in the next chapter
1145 (@pxref{Decoding and Viewing}).
1148 * rfc2045:: Encoding @code{Content-Type} headers.
1149 * rfc2231:: Parsing @code{Content-Type} headers.
1150 * ietf-drums:: Handling mail headers defined by RFC822bis.
1151 * rfc2047:: En/decoding encoded words in headers.
1152 * time-date:: Functions for parsing dates and manipulating time.
1153 * qp:: Quoted-Printable en/decoding.
1154 * base64:: Base64 en/decoding.
1155 * binhex:: Binhex decoding.
1156 * uudecode:: Uuencode decoding.
1157 * yenc:: Yenc decoding.
1158 * rfc1843:: Decoding HZ-encoded text.
1159 * mailcap:: How parts are displayed is specified by the @file{.mailcap} file
1166 RFC2045 is the ``main'' @sc{mime} document, and as such, one would
1167 imagine that there would be a lot to implement. But there isn't, since
1168 most of the implementation details are delegated to the subsequent
1171 So @file{rfc2045.el} has only a single function:
1174 @item rfc2045-encode-string
1175 @findex rfc2045-encode-string
1176 Takes a parameter and a value and returns a @samp{PARAM=VALUE} string.
1177 @var{value} will be quoted if there are non-safe characters in it.
1184 RFC2231 defines a syntax for the @code{Content-Type} and
1185 @code{Content-Disposition} headers. Its snappy name is @dfn{MIME
1186 Parameter Value and Encoded Word Extensions: Character Sets, Languages,
1189 In short, these headers look something like this:
1192 Content-Type: application/x-stuff;
1193 title*0*=us-ascii'en'This%20is%20even%20more%20;
1194 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1198 They usually aren't this bad, though.
1200 The following functions are defined by this library:
1203 @item rfc2231-parse-string
1204 @findex rfc2231-parse-string
1205 Parse a @code{Content-Type} header and return a list describing its
1209 (rfc2231-parse-string
1210 "application/x-stuff;
1211 title*0*=us-ascii'en'This%20is%20even%20more%20;
1212 title*1*=%2A%2A%2Afun%2A%2A%2A%20;
1213 title*2=\"isn't it!\"")
1214 @result{} ("application/x-stuff"
1215 (title . "This is even more ***fun*** isn't it!"))
1218 @item rfc2231-get-value
1219 @findex rfc2231-get-value
1220 Takes one of the lists on the format above and returns
1221 the value of the specified attribute.
1223 @item rfc2231-encode-string
1224 @findex rfc2231-encode-string
1225 Encode a parameter in headers likes @code{Content-Type} and
1226 @code{Content-Disposition}.
1234 @dfn{drums} is an IETF working group that is working on the replacement
1237 The functions provided by this library include:
1240 @item ietf-drums-remove-comments
1241 @findex ietf-drums-remove-comments
1242 Remove the comments from the argument and return the results.
1244 @item ietf-drums-remove-whitespace
1245 @findex ietf-drums-remove-whitespace
1246 Remove linear white space from the string and return the results.
1247 Spaces inside quoted strings and comments are left untouched.
1249 @item ietf-drums-get-comment
1250 @findex ietf-drums-get-comment
1251 Return the last most comment from the string.
1253 @item ietf-drums-parse-address
1254 @findex ietf-drums-parse-address
1255 Parse an address string and return a list that contains the mailbox and
1256 the plain text name.
1258 @item ietf-drums-parse-addresses
1259 @findex ietf-drums-parse-addresses
1260 Parse a string that contains any number of comma-separated addresses and
1261 return a list that contains mailbox/plain text pairs.
1263 @item ietf-drums-parse-date
1264 @findex ietf-drums-parse-date
1265 Parse a date string and return an Emacs time structure.
1267 @item ietf-drums-narrow-to-header
1268 @findex ietf-drums-narrow-to-header
1269 Narrow the buffer to the header section of the current buffer.
1277 RFC2047 (Message Header Extensions for Non-ASCII Text) specifies how
1278 non-ASCII text in headers are to be encoded. This is actually rather
1279 complicated, so a number of variables are necessary to tweak what this
1282 The following variables are tweakable:
1285 @item rfc2047-default-charset
1286 @vindex rfc2047-default-charset
1287 Characters in this charset should not be decoded by this library.
1288 This defaults to @code{iso-8859-1}.
1290 @item rfc2047-header-encoding-alist
1291 @vindex rfc2047-header-encoding-alist
1292 This is an alist of header / encoding-type pairs. Its main purpose is
1293 to prevent encoding of certain headers.
1295 The keys can either be header regexps, or @code{t}.
1297 The values can be either @code{nil}, in which case the header(s) in
1298 question won't be encoded, or @code{mime}, which means that they will be
1301 @item rfc2047-charset-encoding-alist
1302 @vindex rfc2047-charset-encoding-alist
1303 RFC2047 specifies two forms of encoding---@code{Q} (a
1304 Quoted-Printable-like encoding) and @code{B} (base64). This alist
1305 specifies which charset should use which encoding.
1307 @item rfc2047-encoding-function-alist
1308 @vindex rfc2047-encoding-function-alist
1309 This is an alist of encoding / function pairs. The encodings are
1310 @code{Q}, @code{B} and @code{nil}.
1312 @item rfc2047-q-encoding-alist
1313 @vindex rfc2047-q-encoding-alist
1314 The @code{Q} encoding isn't quite the same for all headers. Some
1315 headers allow a narrower range of characters, and that is what this
1316 variable is for. It's an alist of header regexps / allowable character
1319 @item rfc2047-encoded-word-regexp
1320 @vindex rfc2047-encoded-word-regexp
1321 When decoding words, this library looks for matches to this regexp.
1325 Those were the variables, and these are this functions:
1328 @item rfc2047-narrow-to-field
1329 @findex rfc2047-narrow-to-field
1330 Narrow the buffer to the header on the current line.
1332 @item rfc2047-encode-message-header
1333 @findex rfc2047-encode-message-header
1334 Should be called narrowed to the header of a message. Encodes according
1335 to @code{rfc2047-header-encoding-alist}.
1337 @item rfc2047-encode-region
1338 @findex rfc2047-encode-region
1339 Encodes all encodable words in the region specified.
1341 @item rfc2047-encode-string
1342 @findex rfc2047-encode-string
1343 Encode a string and return the results.
1345 @item rfc2047-decode-region
1346 @findex rfc2047-decode-region
1347 Decode the encoded words in the region.
1349 @item rfc2047-decode-string
1350 @findex rfc2047-decode-string
1351 Decode a string and return the results.
1359 While not really a part of the @sc{mime} library, it is convenient to
1360 document this library here. It deals with parsing @code{Date} headers
1361 and manipulating time. (Not by using tesseracts, though, I'm sorry to
1364 These functions convert between five formats: A date string, an Emacs
1365 time structure, a decoded time list, a second number, and a day number.
1367 Here's a bunch of time/date/second/day examples:
1370 (parse-time-string "Sat Sep 12 12:21:54 1998 +0200")
1371 @result{} (54 21 12 12 9 1998 6 nil 7200)
1373 (date-to-time "Sat Sep 12 12:21:54 1998 +0200")
1374 @result{} (13818 19266)
1376 (time-to-seconds '(13818 19266))
1377 @result{} 905595714.0
1379 (seconds-to-time 905595714.0)
1380 @result{} (13818 19266 0)
1382 (time-to-days '(13818 19266))
1385 (days-to-time 729644)
1386 @result{} (961933 65536)
1388 (time-since '(13818 19266))
1391 (time-less-p '(13818 19266) '(13818 19145))
1394 (subtract-time '(13818 19266) '(13818 19145))
1397 (days-between "Sat Sep 12 12:21:54 1998 +0200"
1398 "Sat Sep 07 12:21:54 1998 +0200")
1401 (date-leap-year-p 2000)
1404 (time-to-day-in-year '(13818 19266))
1407 (time-to-number-of-days
1409 (date-to-time "Mon, 01 Jan 2001 02:22:26 GMT")))
1410 @result{} 4.146122685185185
1413 And finally, we have @code{safe-date-to-time}, which does the same as
1414 @code{date-to-time}, but returns a zero time if the date is
1415 syntactically malformed.
1417 The five data representations used are the following:
1421 An RFC822 (or similar) date string. For instance: @code{"Sat Sep 12
1422 12:21:54 1998 +0200"}.
1425 An internal Emacs time. For instance: @code{(13818 26466)}.
1428 A floating point representation of the internal Emacs time. For
1429 instance: @code{905595714.0}.
1432 An integer number representing the number of days since 00000101. For
1433 instance: @code{729644}.
1436 A list of decoded time. For instance: @code{(54 21 12 12 9 1998 6 t
1440 All the examples above represent the same moment.
1442 These are the functions available:
1446 Take a date and return a time.
1448 @item time-to-seconds
1449 Take a time and return seconds.
1451 @item seconds-to-time
1452 Take seconds and return a time.
1455 Take a time and return days.
1458 Take days and return a time.
1461 Take a date and return days.
1463 @item time-to-number-of-days
1464 Take a time and return the number of days that represents.
1466 @item safe-date-to-time
1467 Take a date and return a time. If the date is not syntactically valid,
1468 return a ``zero'' date.
1471 Take two times and say whether the first time is less (i. e., earlier)
1472 than the second time.
1475 Take a time and return a time saying how long it was since that time.
1478 Take two times and subtract the second from the first. I. e., return
1479 the time between the two times.
1482 Take two days and return the number of days between those two days.
1484 @item date-leap-year-p
1485 Take a year number and say whether it's a leap year.
1487 @item time-to-day-in-year
1488 Take a time and return the day number within the year that the time is
1497 This library deals with decoding and encoding Quoted-Printable text.
1499 Very briefly explained, qp encoding means translating all 8-bit
1500 characters (and lots of control characters) into things that look like
1501 @samp{=EF}; that is, an equal sign followed by the byte encoded as a hex
1504 The following functions are defined by the library:
1507 @item quoted-printable-decode-region
1508 @findex quoted-printable-decode-region
1509 QP-decode all the encoded text in the specified region.
1511 @item quoted-printable-decode-string
1512 @findex quoted-printable-decode-string
1513 Decode the QP-encoded text in a string and return the results.
1515 @item quoted-printable-encode-region
1516 @findex quoted-printable-encode-region
1517 QP-encode all the encodable characters in the specified region. The third
1518 optional parameter @var{fold} specifies whether to fold long lines.
1519 (Long here means 72.)
1521 @item quoted-printable-encode-string
1522 @findex quoted-printable-encode-string
1523 QP-encode all the encodable characters in a string and return the
1533 Base64 is an encoding that encodes three bytes into four characters,
1534 thereby increasing the size by about 33%. The alphabet used for
1535 encoding is very resistant to mangling during transit.
1537 The following functions are defined by this library:
1540 @item base64-encode-region
1541 @findex base64-encode-region
1542 base64 encode the selected region. Return the length of the encoded
1543 text. Optional third argument @var{no-line-break} means do not break
1544 long lines into shorter lines.
1546 @item base64-encode-string
1547 @findex base64-encode-string
1548 base64 encode a string and return the result.
1550 @item base64-decode-region
1551 @findex base64-decode-region
1552 base64 decode the selected region. Return the length of the decoded
1553 text. If the region can't be decoded, return @code{nil} and don't
1556 @item base64-decode-string
1557 @findex base64-decode-string
1558 base64 decode a string and return the result. If the string can't be
1559 decoded, @code{nil} is returned.
1570 @code{binhex} is an encoding that originated in Macintosh environments.
1571 The following function is supplied to deal with these:
1574 @item binhex-decode-region
1575 @findex binhex-decode-region
1576 Decode the encoded text in the region. If given a third parameter, only
1577 decode the @code{binhex} header and return the filename.
1586 @code{uuencode} is probably still the most popular encoding of binaries
1587 used on Usenet, although @code{base64} rules the mail world.
1589 The following function is supplied by this package:
1592 @item uudecode-decode-region
1593 @findex uudecode-decode-region
1594 Decode the text in the region.
1602 @code{yenc} is used for encoding binaries on Usenet. The following
1603 function is supplied by this package:
1606 @item yenc-decode-region
1607 @findex yenc-decode-region
1608 Decode the encoded text in the region.
1619 RFC1843 deals with mixing Chinese and ASCII characters in messages. In
1620 essence, RFC1843 switches between ASCII and Chinese by doing this:
1623 This sentence is in ASCII.
1624 The next sentence is in GB.~@{<:Ky2;S@{#,NpJ)l6HK!#~@}Bye.
1627 Simple enough, and widely used in China.
1629 The following functions are available to handle this encoding:
1632 @item rfc1843-decode-region
1633 Decode HZ-encoded text in the region.
1635 @item rfc1843-decode-string
1636 Decode a HZ-encoded string and return the result.
1644 The @file{~/.mailcap} file is parsed by most @sc{mime}-aware message
1645 handlers and describes how elements are supposed to be displayed.
1646 Here's an example file:
1650 audio/wav; wavplayer %s
1651 application/msword; catdoc %s ; copiousoutput ; nametemplate=%s.doc
1654 This says that all image files should be displayed with @code{gimp},
1655 that WAVE audio files should be played by @code{wavplayer}, and that
1656 MS-WORD files should be inlined by @code{catdoc}.
1658 The @code{mailcap} library parses this file, and provides functions for
1662 @item mailcap-mime-data
1663 @vindex mailcap-mime-data
1664 This variable is an alist of alists containing backup viewing rules.
1668 Interface functions:
1671 @item mailcap-parse-mailcaps
1672 @findex mailcap-parse-mailcaps
1673 Parse the @file{~/.mailcap} file.
1675 @item mailcap-mime-info
1676 Takes a @sc{mime} type as its argument and returns the matching viewer.
1686 The Emacs @sc{mime} library implements handling of various elements
1687 according to a (somewhat) large number of RFCs, drafts and standards
1688 documents. This chapter lists the relevant ones. They can all be
1689 fetched from @uref{http://quimby.gnus.org/notes/}.
1694 Standard for the Format of ARPA Internet Text Messages.
1697 Standard for Interchange of USENET Messages
1700 Format of Internet Message Bodies
1706 Message Header Extensions for Non-ASCII Text
1709 Registration Procedures
1712 Conformance Criteria and Examples
1715 @sc{mime} Parameter Value and Encoded Word Extensions: Character Sets,
1716 Languages, and Continuations
1719 HZ - A Data Format for Exchanging Files of Arbitrarily Mixed Chinese and
1722 @item draft-ietf-drums-msg-fmt-05.txt
1723 Draft for the successor of RFC822
1726 The @sc{mime} Multipart/Related Content-type
1729 The Multipart/Report Content Type for the Reporting of Mail System
1730 Administrative Messages
1733 Communicating Presentation Information in Internet Messages: The
1734 Content-Disposition Header Field
1737 Documentation of the text/plain format parameter for flowed text.
1753 @c coding: iso-8859-1