Programming Internet Email

Trends in MUAs

It wasn’t that long ago when all MUAs had textual interfaces. Then came graphical interfaces and attachment support, then the 1994 Internet phenomenon solidified networking around TCP/IP and email around SMTP/MIME/POP/IMAP. Almost all of these MUAs, however, were used manually on a desktop computer. What is next?

The panacea is the concept of “universal messaging,” whatever that phrase will come to mean after various marketing departments get their hands on it. Suppose for a moment that it means that any MUA should be able to send a message to or receive a message from any other MUA. It is a good idea and could actually work with the advent of an open standards approach to messaging.

MUAs are in a period of divergence due to the increase in the number of computing platforms. Palmtop computers, cellular telephones with Internet access, personal digital assistants (PDAs), Web-mail integration, computer-telephony integration, and email-enabled applications are radically changing the face of the mail user agent. The maturing agent technologies, so-called Web ‘bots, are also generally email aware; they may send results messages to their human masters.

In this much more complex Internet, the mail user agent takes on many forms. It can be as small as a PDA IMAP client that allows one to read only partial text messages to a large bloated desktop MUA that natively displays many multimedia MIME types. MUAs may be written in any language, from Emacs Lisp to Java, and may consist ...