We use these, to prevent them from creating accounts in the first place:
- A series of 6 random Q&A Human Verification Options (industry related to forum purpose)
- VB Bad Behavior (checks for mischievous scripts)
- Spambot Stopper (if a bot fills it out too fast, it will reject)
- Glowhost Spam-O-Matic (Checks email and IP against known spammer blacklists. Make sure you DONT have the username checking enabled)
- Mandatory custom fields (industry related, for verification)
- Once email verified, they're moved to a temporary group. Then the mods manually move them to their final security group, and send them a personal welcome email. (based on membership status to our trade org)
The above tools stop 99.9% of them.