Using MIME at Maryland

Most of this documentation is written for use with the unix systems. There is a little information on use with PC and Macintosh systems at the end.

What is MIME?

MIME, the Multi-purpose Internet Mail Extensions, is a freely available specification that offers a way to interchange text in languages with different character sets, and multi-media e-mail among many different computer systems that use Internet mail standards.

Some MIME messages look like plain text but have funny "=D3" sequences sprinkled all over it. This means the message was sent via 'quoted-printable' encoding. Characters that could potentially be lost or converted are escaped into their hex representation and the character set that the sender uses is recorded. This is often used to send text messages because the original message can often be read w/o resorting to decoding as a MIME message.

Other MIME message look like uuencoded files (i.e. a block of random characters about 70 characters wide), but will fail if uuencode is run with it. These are encoded with a similar algorithm, 'base-64'. You will need to decode these files using one of the tools below. Reasons for why base-64 is better than uuencode/uudecode is in the FAQ (3.9). Unfortunately, pine encodes all file-attachments it sends as base-64, regardless of whether it is a text file or not. This is annoying.

I have a MIME message and I don't know what to do

munpack

munpack is a simple tool to decode or extract MIME messages and write the results out to file. It is really intended for binary files that have been sent in an ascii-encoded manner. Example syntax: 'munpack FILENAME'

metamail

metamail is a more versatile and complicated tool. It is actually part of a suite of several tools to handle sending and receiving MIME messages. Running metamail on your message can result in the contents of the message being passed as data to another program to handle. For example, if your MIME message contained an encoded GIF file, a graphical viewer might be run by metamail. If your MIME message contained non-sensical control characters metamail might display your message in an xterm that uses the Hebrew character set, so you could read an ascii version of the Hebrew Calendar. Example syntax: 'metamail -y FILENAME'

I want to send a MIME message

mpack

mpack is a simple tool to encode a file and send it as a MIME message. It is really designed as an equivalent to 'uudecode|split|mail'. Example syntax: 'mpack FILENAME.gif'

metamail

Metamail contains a suite of tools to handle MIME messages. Most of the tools are found in /usr/imports/bin/mm - you will need to add that directory to your path to use them by default.

• mailto - similar to sending messages with Berkeley mail
  • mailto-latin1 - mailto wrapper for European languages
  • mailto-cyrillic - mailto wrapper for Cyrillic
  • mailto-hebrew - mailto wrapper for Hebrew
• metasend - sending files as MIME messages, "intended largely for mail hackers."
• audiosend - record an audio message and then send it as a MIME message.
• metamail.el - In addition, there is an emacs lisp file to run metamail on the contents of a buffer or a region. It can be found in the installed elisp library directory. This module is not loaded in with emacs by default. Explanation of how to use this with emacs is beyond the scope of this document.

Using a MIME capable mail reader all the time

Please consult the MIME FAQ and the document mailers.txt on how to configure mailers to handle MIME messages. If you use a MIME mail reader that supports mailcap facilities (such as exmh), you can consult the specification at RFC1524.

exmh

a tcl/tk-based front end to MH. Powerful and easily configurable. Lends itself easily to tcl/tk hacking. (recommended for X capable workstations)

MH

To read or compose a MIME message, MH must be configured to use mhn, a helper program for MH. Roughly, this means adding the line "mhnproc: mhn" to your .mh_profile (and optionally copying and configuring /usr/imports/lib/mh/mhn_defaults into your Mail directory)

mail (Berkeley)

mail can be configured to read MIME mail by making 'metamail' the program used to page thru a program. Read mailers.txt for examples. Metamail uses your .mailcap and /usr/imports/libdata/mailcap to define actions to take when files of a give type are encountered.

pine

easy to use text based mail reader. pine can also read and post news and was designed to be easy to use. (recommended for terminal use)

elm

only partial support, not recommended. Elm calls metamail when reading any MIME formatted messages (regardless of whether any special processing is needed or not). Sending MIME is "crude". To include attachments, you need to have a line of the form

[include FILENAME CONTENT-TYPE]

You need to know a little about MIME to know whare are valid content-types.

USENET postings that are MIME formatted

MIME with Macintosh & PC

Eudora is available for both Microsoft Windows and Macintoshes. Freebie versions of Eudora can be downloaded from qualcomm.com and fully featured, commercial versions for the Mac can be purchased. These require setting up a POP server on a unix machine - Eudora is just a front-end and the back-end must still reside on a unix system.

Dos and Macintosh versions of mpack and munpack are available from the official distribution site at CMU. A Dos version of pine is available from it's official distribution site as UWashington.