10.1 Smart refiling ¶

When refiling messages, perhaps to archive them, it can be useful to have different target folders for different messages, based on some property of those message — smart refiling.

To accomplish this, we can set the refiling folder (mu4e-refile-folder) to a function that returns the actual refiling folder for the particular message. An example should clarify this:

(setq mu4e-refile-folder
  (lambda (msg)
    (cond
      ;; messages to the mu mailing list go to the /mu folder
      ((mu4e-message-contact-field-matches msg :to
         "mu-discuss@googlegroups.com")
        "/mu")
      ;; messages sent directly to some specific address me go to /private
      ((mu4e-message-contact-field-matches msg :to "me@example.com")
        "/private")
      ;; messages with football or soccer in the subject go to /football
      ((string-match "football\\|soccer"
         (mu4e-message-field msg :subject))
        "/football")
      ;; messages sent by me go to the sent folder
      ((mu4e-message-sent-by-me msg)
       mu4e-sent-folder)
      ;; everything else goes to /archive
      ;; important to have a catch-all at the end!
      (t  "/archive"))))

This can be very powerful; you can select some messages in the headers view, then press r, and have them all marked for refiling to their particular folders.

Some notes:

• We set mu4e-refile-folder to an anonymous (lambda) function. This function takes one argument, a message plist¹⁶. The plist corresponds to the message at point. See Message functions for a discussion on how to deal with them.
• In our function, we use a cond control structure; the function returns the first of the clauses that matches. It’s important to make the last clause a catch-all, so we always return some folder.
• We use the convenience function mu4e-message-contact-field-matches, which evaluates to t if any of the names or e-mail addresses in a contact field (in this case, the To:-field) matches the regular expression. With mu4e version 0.9.16 or newer, the contact field can in fact be a list instead of a single value, such as '(:to :cc)'.