Welcome to mu!

With the enormous amounts of e-mail many people gather and the importance of e-mail messages in our daily work-flow, it is very important to be able to quickly deal with all that - in particular, to instantly find that one important e-mail you need right now.

For that, mu was created. mu is a tool for dealing with e-mail messages stored in the Maildir-format, on Unix-like systems. mu's main purpose is to help you to find the messages you need, quickly; in addition, it allows you to view messages, extract attachments, create new maildirs, … See the mu cheatsheet for some examples. Mu's source code is available in github, and there is the mu-discuss mailing list.

mu includes an emacs-based e-mail client (mu4e), a simple GUI (mug) and bindings for the Guile/Scheme programming language.


  • fast indexing for Maildir, Maildir+ and Maildir-on-VFAT
  • search for messages based on the sender, receiver, subject, date-range, size, priority, words in message, flags (signed, encrypted, new, replied, has-attachment,…), message-id, maildir, tags, attachment (name, mime-type, text) and more
  • support for encrypted and signed messages
  • command-line tools for indexing, searching, viewing, adding/removing messages, extracting attachments, exporting/searching address lists, creating maildirs, …
  • accent/case normalization - so angstrom matches Ångström
  • can be integrated with other e-mail clients such as mutt and Wanderlust.
  • mu4e, an emacs-based e-mail client based on mu (see screenshot).
  • mu-guile: guile 2.0 bindings that allow for scripting, advanced processing of your data, and doing all kinds of statistics
  • fully documented (man pages, info pages)


  • 2014-06-28: mu- released; note: the downloads are now from Github now, and you need to run autoreconf -i after unpacking and before configure.
  • 2013-03-30: released mu-; full with new features and bug fixes – see the download link for some of the details. Many thanks to all who contributed!
  • 2012-10-14: released mu-0.9.9; a new barrage of fixes and improvements – check the link and NEWS. Also, note the mu4e-manual (PDF).
  • 2012-07-01: released mu-; more fixes, improvements (see the link).
  • 2012-05-08: released mu- with even more improvements (the link has all the details)
  • 2012-04-06: released mu-, with many improvements, fixes. See the link for details. NOTE: existing mu and mu4e users are recommended to execute mu index --rebuild after installation.
  • 2012-03-11: released mu-, with a number of fixes and improvements, see the link for the details.
  • 2012-02-17: released mu-, which has a number of improvements to the 0.9.8 release: add mark as read/unread, colorize cited message parts, better handling of text-based message parts, documentation fixes, documentation updates and a few fixes here and there
  • 2012-02-09: moved the mu source code repository to Github.
  • 2012-01-31: finally, mu-0.9.8 is available. It comes with an emacs-based e-mail client, mu4e, and much improved guile bindings. Furthermore, It adds search for attachment mime type and search inside any text part of a message, more tests, improvements in many parts of the code.
  • 2011-09-03: mu 0.9.7 is now available; compared to the -pre version there are a few small changes; the most important one is a fix specifically for running mu on MacOS.
  • Old news

Development & download

Some Linux-distributions already provide pre-built mu packages; if there's no packagage for your distribution, or if you want the latest release, you can download mu source packages from Google Code. In case you find a bug, or have a feature requests, please use the issue tracker.

If you'd like to work with the mu source code, you can find it in Github; also, see the notes on HACKING the mu source code.

There's also a mailing list.

License & Copyright

mu was designed and implemented by Dirk-Jan C. Binnema, and is Free Software, licensed under the GNU GPLv3

© 2011-2014 Dirk-Jan C. Binnema