Re: That newfangled IMAP thing...

[Ted Zlatanov <tzz@lifelogs.com>]

On Sun, 05 Sep 2010 03:04:26 +0200 Lars Magne Ingebrigtsen <larsi@gnus.org> wrote: 

LMI> But I have no idea how it works, really.  You point Gnus at an IMAP
LMI> server, and then what?  How do you tell it how to split your email and
LMI> stuff?

LMI> What's like the minimal work to do if you have a huge nnmail-split-fancy
LMI> rule to go over to being an IMAPper? 

IMAP is a weird protocol with lots of extensions.  It's stateful: you
select a mailbox and then you do things in it.  You can store or
retrieve many types of flags (there's a standard subset).  The
UIDVALIDITY is a really annoying wrinkle, but explaining it would take a
while.  One major issue with IMAP is you can't edit articles, only
append or delete (which is why `e' doesn't work in nnimap groups).

Mailboxes are prefixed and you can find out the server's prefix and path
separator.  For example Courier uses "INBOX" and "." respectively, so
the Maildir path ROOT/a/b/c translates into "INBOX.a.b.c"; I'll use my
Courier setup for the rest of this.

Splitting from INBOX (usually the incoming mail goes there) is pretty
easy as long as you have the server as a primary or secondary.  Here's
my setup:

(defun nnimap-courier-lifelogs-split-fancy ()
  (let ((nnimap-split-fancy nnimap-courier-lifelogs-split-fancy)
        (spam-split-group "INBOX.spam"))
    (nnimap-split-fancy)))

(setq
 nnimap-split-rule '(
 ; ...several servers skipped...
                     ("lifelogs" ("INBOX" nnimap-courier-lifelogs-split-fancy)))
 nnmail-split-methods 'nnmail-split-fancy
 nnimap-split-inbox "INBOX"
 nnimap-courier-lifelogs-split-fancy '(|
                      (: gnus-registry-split-fancy-with-parent)
                      (: spam-split 'spam-use-regex-headers)
; ...
                      (any "cfengine"   "INBOX.cfengine")
; ...
                      (: spam-split)
                      ;; default mailbox
                      "INBOX.mail"))

I may be forgetting something, but basically you need 

1) the nnimap-split-rule for your server
2) the split-inbox "INBOX"
3) the actual split rules

and the rest is automatic.  I prefer this setup to server-side splitting
because of my gnus-registry and spam-split needs.

If you need a Courier account I can set you up (but with a Maildir
backend it's really trivial to set it up yourself).  IMO dovecot is
better but I haven't gotten around to switching in years now.  GMail's
IMAP support is weird: their mailboxes are tags and a message can be in
more than one mailbox.

HTH
Ted