On my Gossamer Forum, I am getting massive spam signups from domains like sohu.com, 163.com, tom.com, qq.com and others. In the last three days alone, about 50 of these.

Now, I have my signup procedure set for manual confirmation by me (the moderator.) So they've done the login procedure and then responded to the validation email. They aren't getting into my forum because I'm manually filtering all of these out.

I'd like to find a way to modify Gossamer Forum to block these 'bots (or whatever they are) from doing this automatically. What can be done?

Many Thanks in Advance,
Mark