I'm looking for a very good PHP/MySQL based forum script that is free, either freeware, GPL, etc. But the main thing is that it must have EXCELLENT false-account rejection capabilities. I've used Simple Machines Forum, PHPBulletin Board and several others, and they all work well for a while, then apparently are compromised and before you know it I have 100 bogus G-Mail users signed up. So if there is not a way to keep them out, I then at least need a forum that will let me mass-delete users instead of one-at-a-time.

I really want to keep an open forum going, and I really like participating in them, but the spammers are making life miserable. I would appreciate suggestions/nominations for the best free script available, And thanks to everyone who contributes any serious answer.