What is MH?

MH is a Message Handling system originally developed at RAND, then improved and widely distributed by the University of California at Irvine. MH is an MUA designed with the UNIX philosophy of ``create lots of small tools that do simple things well, and provide a flexible way to put them together to do things.'' This tool philosophy is very different from the application philosophy that some people have, in which just one program should do everything.

MH is for people who understand why UNIX is the way it is and like it. If you hate UNIX and wish you were just using a Mac or something else, forget MH; use Elm or something else.

Why might I consider MH?

MH offers a variety of features, many of them not present (or not as flexible) in other user agents.
Most mailers are monolithic; you ``get into'' the mailer and then do stuff within it. MH commands are generally issued directly from the shell; thus all the normal flexibility and power of shell features (e.g. aliases, functions, history) are still available.
MH consists of several small programs which perform various primitive message handling tasks. Naturally, if monolithicity is desired, it is simple to build a conventional mail application on top of these tools; mh-e is one that runs inside Emacs, exmh runs in X under Tcl/Tk, and many others are discussed in the MH FAQ.
Ease of expandability
Monolithic applications typically work well as long as the task desired was one anticipated by the application designer, but adding novel functionality is much simpler in a modular system. It is no accident, for instance, that MH offered the first (and, thus far, still the best) support for MIME among mailers used here, or that MH had the first (and still has the best) clean interface with implementations of PEM.
MH offers a real customization language, not just a screen full of options (most of them mere chrome) which may be toggled on or off. You get all the shell power of macros, functions, etc. as well as a full language for specifying mail processing. You don't have to learn much of this just to use MH, but all that power is there if you need it later.
Non-interactive use
It is possible (often pretty easy) to perform MH processing in a batch environment (say, from a shell script.) Most other mailers only allow simple sending of mail non-interactively.
Compliance with standards
MH works with MIME and meets earlier specifications on message format, message encapsulation, and the like. Some other mailers pay less mind to such things; for example, it has been eight years since forwarding standards were adopted, but Elm still isn't compliant with them. For that matter, Elm violates some sections of RFC 822.
When messages are replied to, forwarded or redistributed, an annotation recording that event may automatically be attached to the message in question for future reference.
File-per-message storage
The silly concept of a ``mailbox'' with many messages is replaced with a proper directory. This makes MH typically much faster at handling folders with large numbers of messages (unlike Elm, where you get to watch while it counts up the number of messages in your inbox.) Using ordinary UNIX file manipulation techniques also becomes trivial.
If all that sounds complicated, note that you really only need to learn 5 commands to start using MH for your mail:
Incorporates newly delivered mail into your inbox
Lists messages in a folder
Displays messages
Composes new messages
Replies to existing messages

So how can I find out more?

  • RTFM
  • Look in the MH Documentation archive. Some of the material is a bit dated, but still useful; it includes current documentation with a brief tutorial (no need to print this long thing out; a copy is in the usual place Dueber keeps some stuff.) Some effective use of MH is discussed in the classic How to process 200 messages a day and still get some real work done.
  • For MIME info, peruse some info on MIME, and a tutorial on using MIME with MH
  • Look at people's MH configuration; for instance, here is the author's .mh_profile
  • If all else fails, ask in cs.unix.questions; somebody knows.
  • Good luck, and happy MHing!

    Marc V 12-93