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Save Hours by Reading Mailing Lists in Emacs Over IMAP

Emacs’ built-in newsreader Gnus is made for efficiently keeping up with high-volume lists; I show how to hook it into your IMAP account.

With features like configurable message threading, kill-files and per-thread and per-poster scoring, Gnus has the potential to save a lot of the time you would normally spend wading through high-volume mailing lists.

Nowadays most people read mailing lists via IMAP-enabled mail accounts, e.g. Gmail. Gnus supports IMAP directly, but it doesn’t work well when the remote folders have thousands of messages, as is the case with many mailing lists. As a workaround, we can use offlineimap to maintain a local copy of our folders. As a side benefit, we can then read mail off-line.

(Update: since this article was written, Gnus IMAP support has improved, so the following steps may or may not be strictly necessary.)

We can use the excellent Dovecot to provide an IMAP interface to that local copy so that Gnus can access it; and we can do this without configuring Dovecot as a full IMAP server, which would need to run constantly and be configured for authentication etc.

On a Mac, you can install dovecot and offlineimap with Homebrew, MacPorts or, presumably, Fink.

In ~/.dovecotrc:

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protocols = imap
mail_location = maildir:~/Library/Caches/OfflineImap
auth default {
}

And in ~/.offlineimaprc:

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[general]
accounts = Mail
maxsyncaccounts = 1
ui = TTY.TTYUI
[Account Mail]
localrepository = Local
remoterepository = Remote
[Repository Local]
type = IMAP
preauthtunnel = dovecot -c ~/.dovecotrc --exec-mail imap
[Repository Remote]
type = IMAP
# or "type = Gmail", if applicable
remotehost = my.mail.server
remoteuser = myuser
remotepass = mypassword
ssl = yes
maxconnections = 1
realdelete = no
folderfilter = lambda foldername: re.search("^Lists\.", foldername)

Now, simply running “offlineimap” should sync your mailing lists into ~/Library/Caches/OfflineImap. (You’ll need to do this regularly, e.g. before and after reading your lists. Julien Danjou recently wrote a nice elisp wrapper for offlineimap.)

All that remains is to tell Gnus how to access your local mail cache.

In .gnus:

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(setq imap-shell-program "dovecot -c ~/.dovecotrc --exec-mail imap")
(setq gnus-select-method '(nnimap "Mail"
                                  (nnimap-stream shell)))

Now you can start Gnus with M-x gnus, and then press ^ to enter the server buffer. Drill down into the “nnimap+Mail” server and use u to subscribe to each of the mailing lists. They should then appear in Gnus’ main *Group* buffer.

That’s enough to get started reading mail more efficiently, and as with all things Emacs, there’s great potential for customising Gnus to suit your own preferences.

Further reading

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