On a Debian Squeeze system I run an IMAP server using Dovecot with messages being stored in the Maildir format. The server is accessed by various clients, including Thunderbird, Evolution and RoundCube.
When a user deletes a message it is moved to the Trash folder. (I am unsure if all clients also mark the messages as deleted when moving them.) However, beyond that no action is taken. Hence I am forced to periodically remind all users to explicitly empty their Trash every few months.
Does Dovecot provide an easy means of automatically deleting Trashed messages older than n days? I've seen mention to an expunge cron-job but it seems to delete all messages older than a certain number of days as opposed to just those in Trash.