man > mh-mime(7)

MH-MIME(7mh)                                                                            MH-MIME(7mh)

NAME
       mh-mime - overview of nmh MIME message composition and display

DESCRIPTION
       The  acronym  MIME  stands  for Multipurpose Internet Mail Extensions, the format of Internet
       messages used to send multi-media content.  The nmh command suite has support for the display
       and composition of MIME messages, but currently MIME support  is  not  completely  integrated
       into  all  tools.   This document provides an overview as to which tools support MIME message
       display, storage, and composition.

   Local Character Set Conversion
       All of the nmh commands convert non-native character sets to  the  local  character  set,  as
       specified by the operating system locale settings.  See locale(1) for more details on the en‐
       vironment  variables used to set the local character set.  Character set conversion will only
       take place if nmh was built with iconv(3) support.   See  mhparam(1)  for  how  to  determine
       whether your nmh installation includes iconv(3) support.

       Depending on the source and target character set, it may not be possible to convert all char‐
       acters  to  the  local character set.  In this case a substitution character will be used for
       the characters that cannot be converted.

   Message Display
       The default format used by scan(1) will automatically decode MIME-encoded  headers.   If  you
       have  a custom scan format, see the examples provided with the nmh distribution (found in the
       “/etc/nmh” directory) and mh-format(5) for details on how to make sure your MIME headers  are
       properly decoded.

       By  default, if show detects that it is reading a MIME message it will invoke mhshow(1).  The
       default behavior of mhshow is to only display text parts that are not marked as  attachments.
       See mhshow(1) for details on how to control what mhshow will display.

   Message Interrogation and Storage
       The  mhlist(1)  command  will display a listing of the MIME parts contained within a message.
       That information can be used in conjunction with the mhstore command to save individual parts
       or content types of a message.  See mhlist(1) and mhstore(1) for more details  on  how  these
       commands work.

   Message Composition and Reply
       All  messages  sent  by  send(1)  will  automatically be processed by mhbuild(1) before being
       passed to post(1) for message submission.  mhbuild will use the locale settings to mark  text
       content  with the appropriate character set and apply any necessary encoding.  If you wish to
       include text in your message using a character set that does not match your locale, you  will
       need  to specify the character set using an mhbuild directive; see mhbuild(1) for more infor‐
       mation.

       For attaching files or composing other non-text content, there are two  options:  the  attach
       system and mhbuild directives.

       The  attach system is best suited for content where one or more files are being attached to a
       message.  You can use the attach system by either using the attach command at the “What now?”
       prompt, or by inserting an “Attach:” header in the message draft containing the name  of  the
       file  you  wish  to  attach to the message (note that all the attach command does is place an
       “Attach:” header in the message draft).  mhbuild will then automatically include  the  speci‐
       fied  file(s) in the outgoing message.  See send(1) for details on how mhbuild determines the
       proper content type of attached files.

       The other method of composing MIME messages is to use mhbuild directives.  This allows  exact
       control  over the contents and format of the MIME message, but has a more complicated syntax.
       mhbuild(1) contains details on the directive syntax and examples of directives for  different
       media  types.   It  is important to note that when using mhbuild directives the user must run
       mhbuild outside of send to have it process directives; when being run  by  send,  mhbuild  is
       configured  to  not  process  directives so normal user text is not mistaken for a directive.
       When using directives a user typically uses the mime command at the  “What  now?”  prompt  to
       process them.

       When  replying  to messages using repl(1) the traditional MH method of including the original
       text in the reply does not interoperate with  MIME  messages.   The  -convertargs  switch  to
       repl(1)    provides    one    solution.     Another    solution:    the   contrib   directory
       (/usr/share/doc/nmh/contrib) contains a Perl program called  replyfilter  which  will  decode
       text  parts and present them in an appropriate manner to be included in a message reply.  See
       the comments at the top of replyfilter for instructions on how to configure nmh to work  with
       it.

   Message Rewrite
       The  mhfixmsg(1) command can apply various transformations to MIME messages, including decod‐
       ing of text parts, converting the character set of text parts, and  insertion  of  text/plain
       parts  to  correspond  to  text parts of other subtypes.  mhfixmsg can also repair defects in
       MIME messages, such as mismatched top-level boundary indicators and invalid Content-Transfer-
       Encoding values.

SEE ALSO
       comp(1), iconv(3), mh-format(5), mhbuild(1), mhfixmsg(1), mhparam(1), nmh(7), repl(1),  what‐
       now(1),
       /usr/share/doc/nmh/contrib/replyfilter,
       /usr/share/doc/nmh/contrib/replaliases

BUGS
       MIME support should be more integrated into all of the nmh tools than it currently is.

nmh-1.8                                      2014-12-15                                 MH-MIME(7mh)