Forum security and managing spammers

[BonsaiNut]

I have numerous bots registering at my site. The combination of email confirmation and moderation captures them all, but requires a lot of manual effort. Once I catch spammers I add as many as possible to my banned email addresses and domains, but I can't do this in one particular case. There is a certain bot out there that registers several times a day on my forum with this format:

*z*@hotmail.com

The asterisk is a wildcard character that represents a text string - in most cases a name. So, for example, registrations will be from:

adamzschultz@hotmail.com
terazsmith@hotmail.com

I have tried manually adding these to my banned email lists, but the combinations are practically unlimited, and even after blocking over 30 of these, they still keep coming. In addition, they all pass the email confirmation test, so they clog up my moderation queue.

If there was a way to add wildcards to our blocked emails I'd have this resolved immediately. There may be a manual way to fix this, but it escapes me.

Any suggestions?