I didn't figure out my PM inbox was full until I read a reply by some guy attempting to reach me on a thread. The PM inbox should tell you when you have run out of space and how much space you are consuming. Also, when you empty out your PM mailbox, the server should take thouse messages in people's outboxes and resend them. Furthermore, a "notice feature" should be implemented so that when you have a filled up inbox, you at least KNOW that someone PM'd you and you have a way of getting back to them.