There is a script pclean provided, that can be used for all sorts of cleanup chores. At the moment this script is in beta state and not all that well tested.
In the meantime the following three scripts in the scripts directory can be used for nightly cleanup chores:
To aid in recovery after accidential deletion of a mailbox, the mailbox is not really deleted but saved under a different name. This script will check the lists of configured mailboxes in /etc/popular/mb/* and rename all mailboxes not in one of these files. The new name is simply the old name with the date/timestamp appended.
This script expires mails in mailbox after a configurable time. The time can be configured differently for each namespace. Deleted mailboxes have their own expire time. Additionally, this script will remove deleted mailbox directories, when there are no mails left.
This script checks the size of all mailboxes. Mailboxes who are above or near the quota are logged. Additionally a message is put into the mailbox to notify the user about his full or nearly full mailbox.