procmail and delivering to an IMAP server?

Question

I run my own mail server. It uses procmail to filter incoming mail, which is then stored in maildirs and gets served out my MUA using IMAP. I've got about 1.5GB of email is 135000 inodes.

This all works very nicely. However, I'd rather like to stop using maildir and switch to something more efficient --- maildb, or Dovecot's dbox, for example. Unfortunately, procmail can only deliver to a very limited set of backing store formats (Maildir, MH and mbox, AFAICT).

What I'd really like to do is to persuade procmail to deliver email via IMAP, rather than writing it directly to the backing store; this means that I can change the backing store format whenever I like without needing to reconfigure procmail. But I can't find any way of doing this. Any ideas?

(I'm also interested in any other mail filter tools that work like procmail but support IMAP. The only other filter tool I know is maildrop --- but that has similar restrictions to procmail.)

Answer 1

Okay, here's a proper solution.

The cone project (http://www.courier-mta.org/cone/cone00index.html, Debian project: cone) has a very handy tool called mailtool which will copy files between mailbox types, including remote IMAP servers.

So, to deliver a message to a remote mailbox, you need a script which:

• writes out the incoming message to a file (which becomes a one-message mbox folder)
• does mailtool -tofolder destinationfolder -copyto imaps://username:password@server.com mbox:/full/path/to/message.mbox

That will then upload the message.

I don't actually need to do this any more so don't have a prepared script to post, but of the eight or nine different IMAP tools available, this was the only one that would actually do this, so it's worth documenting as such.