On MUAs

What is a MUA?

MUA stands for Mail User Agent. MUAs present previously received mail messages to users, help them to store and archive the latter and compose and spool new messages for further delivery. Usually MUAs do not transfer the mail data to remote hosts themselves, but leave this part of the job to MTAs (Mail Transfer Agents). However, more and more MUAs nowadays also offer the option to directly send mail using SMTP.

Console based MUAs

  • mail was the first "tool" being available on Unix systems to read and write mail. It uses the terminal console for text editing which, of course, is not too comfortable, because it restricts editing to single lines - just the same as within command lines.
  • Sendmail, as well as the compatibility modes of its successors, offer reading from stdin. This allow users to send mail messages by directly calling sendmail.

Terminal based MUAs

  • elm
  • pine
  • mutt
    All of these MUAs make use of the capabilities of the terminal. Users can use their favourite text editor for compositing mails, attach additional files, manage folders, call external programs like text encoders and decoders, aso. Because the output is terminal based tools like these can be used for working on remote hosts as comfortable as working on local machines.

X-based MUAs

  • xmh was the first MUA for the X Window System. Its graphic output is based on the Athena X-Toolkit allowing it to make use of this toolkit's widgets and text editing facilities. xmh introduced the xmh mail folder format, which was necessary to maintain several mail folders at once.
  • kmail represents the state-of-the-art MUA for the KDE Desktop Environment. The latest versions of kmail support direct SMTP-delivery, POP and IMAP and several user identities.
  • balsa
    spruce
    althea
    These three programs represent the GTK-counterpart to the Qt-based kmail, with balsa being the most featured.

Last modified at 1999-10-10.