Very, very, very good idea. More control of PMs is a must nowadays due to the way in which spammers abuse this feature.
The Admin should be able to:
- limit this feature accodring to a users # of posts/date of registration, this way newbie registrations cannot start sending PMs straight away
- limit the number of PMs users can send daily/weekly, or at least alert the admin quietly if a user is sending more than X amount of messages daily
- filter PM content for abuse. This would first and foremost scan for certain key words or URLs, but also if a user decides to cut&paste the same message over and over then the system would alert the Admin that someone is sending the same message numerous times.
- PM search feature: the Admin should be able to do a forum-wide scan of all PMs in search of certain words, much like searching regular posts. When a spammer is uncovered there might be a URL he is sending out that is not on the banned/watched list - by scanning all PMs the Admin would be able to track down his accomplices who might also be spamming users with the same info.
