Flood control: anti-spam scripts/hacks

[eleventh]

Does anybody know where I can find a script or hack to prevent spamming. For example, if i'm not on the board/online how do I prevent someone from automatically or manually spamming my site. The delay feature doesn't work if the spammer is persistent. I'm looking for something that temporarily bans a member when he posts the same thing more than 5 times.

[Dean C]

Moved to General vBulletin Questions. Please red the forum descriptions more closely in future Thanks.