On Tue, 2009-02-24 at 17:41 -0500, Neil wrote:

Inspired by the "Dovecot as a email storage system" thread...

Is there a way to instruct Dovecot go into read-only mode for an account, or a mailbox?

ACL plugin would be one possibility. It won't prevent creating new mailboxes though.

Could I maybe fake it by setting perms on the maildir directory to 440?

Yes, but if you do that, change the control and index directories to somewhere else where they can be written to.