Sorry for the PM spam from that user the other day. What happens on Vbulletin is that a user will register an account and even though I have to approve their account to give them access to post, they end up in the Registered Users group before the approval process which gives them access to the PM system. I've looked in the past for a good extension that limits the PM system until you have a certain number of posts but I couldn't find one. I guess I should start looking again.