Quoting Chris Wakelin c.d.wakelin@reading.ac.uk:
I guess you're delivering mail to /var/mail/username, and UW-IMAP "snarfs" (to use the UW term :)) the messages to ~/mbox (if it exists) whenever the user opens INBOX in IMAP.
Yes, we used to do this also, but we stopped when we went to dovecot.
Since we're a small installation, we just merged the ~mbox files back into the /var/spool/mail/username files...
Since the person posting the question has 30K users, this may not be feasible. Depends on what percentage of them use the ~mbox feature.
It might also be possible to write a Dovecot plugin to emulate the UW-IMAP "snarf" behaviour, but as far as I know, nobody has.
AFAIK there is none also, but one would be "way cool" to have...
I have to say that our UW-IMAP -> Dovecot transition was painless (transparent!) and that the performance gains were huge (otherwise we'd still be "pruning" user's INBOXes into folders for them every few months).
I agree completely. No one noticed anything except for the blazing performance change, and I also was able to stop "pruning" user's inboxes. Was not only painless, but removed a lot of existing pain!
Best Wishes, Chris
-- Eric Rostetter The Department of Physics The University of Texas at Austin
Go Longhorns!