Sloggers can still register a blog

Hello,

When I upgraded to wordpress 3, the splogging problem twice as doubled, I’m not sure if it’s an upgrade issue. Because of this, I had my wpmu site disabled multisite features. However, even without multisite features, these losers are still making new accounts and blogs. I don’t understand how they manage to get past my settings when I already set my configuration to account registration only.

And also, is it possible to limit allowed emails to @yahoo.com or @gmail.com. These spammers run past my email validation checks by using other email accounts.