The Quota and Deletion agents are pretty awesome - but today it would be even better if it could work a little more smartly and actually start deleting (FIFO) emails as soon as the mailbox quota is to be breached such that the user loses a couple of oldest emails to make room for a new one but never is the user's mailbox then blocked because it is "full".
People ignore the quota warnings,mark them as spam, don't know what it means, etc etc. Would be nice if the issue could be resolved by simply revolving the emails out and into the mailbox when the mailbox is full instead of blocking the mailbox from any new emails altogether.