Manual Reference Pages - MH-MIME (7)
mh-mime - Overview of
MIME message composition and display
The acronym MIME stands for Multipurpose Internet Mail Extensions, the
format of Internet messages used to send multi-media content.
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
for more details on the environment variables used to set the
local character set. Character set conversion will only take place if
nmh was built with
support. See the
man page for how determine whether your
nmh installation includes
Depending on the source and target character set, it may not be possible
to convert all characters to the local character set. In this case a
substitution character will be used for the characters that cannot be
The default format used by
will automatically decode MIME-encoded headers. If you have a custom
scan format, see the examples provided with the
nmh distribution (found in the
/usr/local/etc/nmh directory) and
for details on how to make sure your MIME headers are properly
By default, if
show detects that it is reading a MIME message it will invoke
The default behavior of
mhshow is to only display text parts that are not marked as attachments. See
for details on how to control what
mhshow will display.
Message Interrogation and Storage
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
for more details on how these commands work.
Message Composition and Reply
All messages sent by
will automatically be processed by
before being passed to
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 a
mhbuild directive; see
for more information.
For attaching files or composing other non-text content, there are two options: the attach system and
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
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 (it should be noted all that the
attach command does is place an Attach header in the message draft).
Mhbuild will then automatically include the specified file(s) in the outgoing
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.
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
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
the traditional MH method of including the original text in the reply does
not interoperate with MIME messages. As of this writing there is no
native solution for addressing this issue, but the contrib directory
(/usr/local/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.
command can apply various transformations to MIME messages, including
decoding of text parts, converting the character set of text parts,
and insertion of text/plain parts to correspond to text parts of other
mhfixmsg can also repair defects in MIME messages, such as mismatched top-level
boundary indicators and invalid Content-Transfer-Encoding values.
MIME support should be more integrated into all of the
nmh tools than it currently is.
|nmh-1.6 ||MH-MIME (7) ||March 16, 2014 |
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