mu

Welcome to mu!

Latest development news: NEWS.org.

With the enormous amounts of e-mail many people gather and the importance of e-mail message in our work-flows, it’s essential to quickly deal with all that mail - in particular, to instantly find that one important e-mail you need right now, and quickly file away message for later use.

mu is a set of command-line tools for dealing with e-mail messages stored in the Maildir-format. mu’s goal is to help you to quickly find the messages you need, view them, extract attachments, and so on.

After indexing your messages into a Xapian-database, you can search them through a query language. You can use various message fields or words in the body text to find the right messages.

Built on top of mu are some other tools (included in this package):

• mu4e: a full-featured e-mail client that runs inside emacs (more below)
• mu-scm: bindings for the Guile/Scheme programming language (version 3.0 and later)

mu is written in C++; mu4e is written in elisp and mu-scm is written in a mix of C++ and Scheme.

mu is available in many Linux distributions (e.g. Debian/Ubuntu and Fedora) under the name maildir-utils; apparently because they don’t like short names. All of the code is distributed under the terms of the GNU General Public License version 3 (or higher).

The mu project welcomes contributions; see the Github issue list and IDEAS.org.

Users and developers are encouraged to join the mu-discuss mailing-list.

Versions

mu attempts to balance development speed and stability.

Active development takes place on master (the 1.14 series), and we maintain release/1.12 as well, for any critical fixes.

Every few months, we release a stable version (e.g. 1.14.0); development then continues in master, with -pre<n> (e.g. 1.14.1-pre1): -pre-suffixed versions refer to the current development code, until it is released (and then looses its -pre suffix, i.e., becomes the 1.14.1 release).

Hence, generally we recommend the latest 1.14 release; if you want to avoid any changes except critical bug-fixes, use the latest 1.12 release; and finally, if you want to track active development, use master.

Overall, we try to avoid incompatible changes, but sometimes this is necessary, for example to update the versions of required libraries.

Installation

Note: building from source is an advanced subject, especially if something goes wrong. The below simple examples are a start, but all tools involved have many options; there are differences between systems, versions etc. So if this is all a bit daunting we recommend to wait for someone else to build it for you, such as a Linux distribution. Many have packages available.

Requirements

To be able to build mu, ensure you have:

• a C++20 compiler (gcc and clang are known to work)
• development packages for Xapian and GMime and GLib (see meson.build for the versions)
• basic tools such as make, sed, grep
• meson

For mu4e, you also need emacs, version 28 or later.

Note, support for Windows is very much experimental, that is, it works for some people, but we can’t really support it due to lack of the specific expertise. Help is welcome!

Building

$ git clone https://github.com/djcb/mu.git
$ cd mu

mu uses meson for building, so you can use that directly, and all the usual commands apply. You can also use it indirectly through the provided Makefile, which provides a number of useful targets.

For instance, using the Makefile, you could install mu using:

$ ./autogen.sh && make
$ sudo make install

You can of course also run meson directly (see the meson documentation for more details):

$ meson setup build
$ meson compile -C build
$ meson install -C build

Initial setup

Most mu commands and mu4e require setting up the database, which is needed only once. For this, there is the mu init command. See its manpage for all the details, but could look something like:

$ mu init --maildir=~/Maildir          \
    --personal-address=jim@example.com \
    --personal-address=bob@example.com \
    --ignored-address='.*reply*.'

This creates your database, specifies some of your personal addresses, and some addresses (a regular expression) that should be ignored from the contacts-cache used for address-autocompletion in mu4e.

After this step, we can index our maildir:

$ mu index

The first time you do this, it can take a few minutes, depending on how many messages you have. Afterwards, you can run mu index e.g., after retrieving messages from a remote server.

After that has completed you can try to find some messages with some simple queries:

$ mu find hello

Mu4e

Mu4e is an e-mail client for GNU/Emacs that works on top of mu.

mu4e is shipped as part of the mu package, and the versions must match.

Since there are so many different ways people use e-mail, there are a lot of ways to customize it to your needs; see the Mu4e Reference Manual for all the details, here we include quick-start instructions, in the form of use-package declaration. Much of it is commented-out, pick the parts that best fit your particular needs; see the manual for a deeper dive.

(use-package mu4e
  :ensure nil
  :config
;;;; Basics

  ;; (setq mu4e-mu-binary "/path/to/mu") ; only needed if mu is not in PATH
  (setq mail-user-agent 'mu4e) ;; mu4e as the default emacs mail program

  ;; Identify yourself. Not strictly necessary.
  ;; (setq
  ;;  user-mail-address "mickey@example.com"
  ;;  user-full-name "Mickey Mouse")

  ;;
;;;; Retrieving mail
  ;;
  ;; Here, put the command you use for getting mail from some
  ;; remote server to your local Maildir. You can leave it at its
  ;; default when you have local delivery (rare these days)
  ;;
  ;; The command depends on your local setup, e.g.:
  ;; "offlineimap", "mbsync", "fetchmail", ... or some shell script
  (setq mu4e-get-mail-command "/bin/true" ;;
        mu4e-update-interval 180)         ;; check every 3 minutes

  ;;
;;;; Reading mail
  ;;
  ;; You need to tell mu4e where it can find certain mail folders
  ;; in your Maildir; these are the paths relative to your maildir-root.
  ;; (setq
  ;;  mu4e-inbox-folder  "/inbox"
  ;;  mu4e-sent-folder   "/sent"
  ;;  mu4e-drafts-folder "/drafts"
  ;;  mu4e-trash-folder  "/trash")
  ;;
  ;; For Gmail, these could look something like:
  ;; (setq
  ;;  mu4e-inbox-folder  "/INBOX"
  ;;  mu4e-sent-folder   "/[Gmail]/Sent Mail"
  ;;  mu4e-drafts-folder "/drafts"
  ;;  mu4e-trash-folder  "/trash")
  ;; ;; (here we keep /drafts & /trash local)

  ;; define some shortcuts to maildirs you use often
  ;; the :key defines the shortcut key, the other parameters
  ;; determine what is (not) shown in the main-view. See the
  ;; `mu4e-maildir-shortcuts' docstring.
  ;; (setq mu4e-maildir-shortcuts
  ;;       '((:maildir "/inbox"       :key ?i :hide-if-no-unread t :favorite t)
  ;;         (:maildir "/lists"       :key ?l :hide-if-no-unread t)
  ;;         (:maildir "/sent"        :key ?s :hide-unread t))))

  ;; Defaults to homedir. Can also be a function, for file-specific
  ;; dirs; see docstring.
  ;; (setq mu4e-attachment-dir "~/Downloads")

  ;;
;;;; Sending mail
  ;;
  ;; Mail sending goes through the Emacs smtpmail package
  ;; the exact settings depend on your SMTP provider
  (setq
   send-mail-function          smtpmail-send-it
   message-send-mail-function  smtpmail-send-it
   ;; smtpmail-smtp-user          "user@example.com"
   ;; smtpmail-smtp-server        "smtp.example.com"
   ;; smtpmail-smtp-service       465
   ;; smtpmail-stream-type        'tls
   )

  ;;
;;;; Extras
  ;;
  ;; There are *many* more settings to customize mu4e. Here are a few common
  ;; ones; just some examples, tweak to your preferences.

  ;; prefer text when mails have both text and html
  ;; (with-eval-after-load "mm-decode"
  ;;   (add-to-list 'mm-discouraged-alternatives "text/html")
  ;;   (add-to-list 'mm-discouraged-alternatives "text/richtext")
  ;;   (add-to-list 'mm-discouraged-alternatives "multipart/related"))

  ;; Some visual tweaks
  (setq mu4e-use-fancy-chars t) ;; allow for unicode emojis

  ;;
  ;;;; Custom bookmarks / queries
  ;; e.g.:
  ;; (add-to-list 'mu4e-bookmarks
  ;;              '( :name  "Inbox messages in the last 7 days"
  ;;                 :query (lambda ()
  ;;                          (format "maildir:/inbox AND date:%s"
  ;;                                  (format-time-string
  ;;                                   "%Y%m%d.."
  ;;                                   (subtract-time (current-time)
  ;;                                                  (days-to-time 7)))))
  ;;                 :key   ?w))

  ;; Tweak headers display; i.e. what headers to show, sizes etc.
  ;; Eg:
  ;; (setq
  ;;  mu4e-headers-date-format "%Y-%m-%d"
  ;;  mu4e-headers-time-format "%H:%M"
  ;;  mu4e-headers-fields
  ;;  '((:human-date     .  10)
  ;;    (:flags          .  4)
  ;;    (:from-or-to     .  20)
  ;;    (:mailing-list   .  8)
  ;;    (:maildir        .  8)
  ;;    (:labels         .  8)
  ;;    (:thread-subject .  nil)))

  ;; Refiling a messages ('r'), i.e., move messages to some other folder,
  ;; based on their properties. mu4e-refile-folder can be a folder-name
  ;; or a function taking a message and returning a folder-name
  ;; (setq mu4e-refile-folder
  ;;         (lambda (msg)
  ;;           (cond
  ;;            ;; all messages sent by me go to the sent folder
  ;;            ((mu4e-message-sent-by-me msg) (mu4e-get-sent-folder msg))
  ;;            ;; all mu-related messages go to the mu folder
  ;;            ((mu4e-message-contact-field-matches msg :to
  ;;                                                 "mu-discuss@googlegroups.com")
  ;;             "/mu")
  ;;            ;; some work-related senders
  ;;            ((seq-some
  ;;              (lambda (addr) (mu4e-message-contact-field-matches msg :from addr))
  ;;              `(,(rx "boss@company.com" eos)
  ;;                ,(rx "lucy@bookkeeper.com" eos)
  ;;                ,(rx "jim@taxes.gov" eos)))
  ;;             "/work")
  ;;            ;; everything else goes to /archive
  ;;            (t
  ;;             "/archive"))))

  ;; Tweak the message-view
  ;; (setq
  ;;  mu4e-view-date-format "%Y-%m-%d %H:%M"
  ;;  mu4e-view-fields
  ;;  '(:from :to :cc :bcc :subject :flags :date :maildir :mailing-list))

  ;; with nerd-icons or all-the-icons installed, you can get some icons when
  ;; view messaages, e.g.
  ;; (setq mu4e-file-name-to-icon-function #'nerd-icons-icon-for-file)
  ;;  or
  ;; (setq mu4e-file-name-to-icon-function #'all-the-icons-icon-for-file)

  ;; Set a message signature:
  ;; (setq message-signature
  ;;       (concat
  ;;        "User McUserFace\n"
  ;;        "http://www.example.com\n"))

  :hook
  ;; tweak the composer
  ((mu4e-compose-mode . (lambda ()
                          (set-fill-column 72)
                          (flyspell-mode)))
   ;; allow for inserting attachments with dired,
   ;;   with `M-x gnus-dired-attach'
   (dired-mode  . turn-on-gnus-dired-mode))

  :bind ;; the Mu4e transient menu
  (("C-c m" . mu4e-transient-menu)))