I visit another forum often that is run on vB and they have a add-on that stops almost all spammers and doesn't accidentally filter real accounts/posts. (I know i sound like I'm payed to do this but I'm not...) vB 4.X.X: http://www.vbulletin.org/forum/showthread.php?t=248042 vB 3.8.X: http://www.vbulletin.org/forum/showthread.php?t=248470