Can I block registrations from a specific email service provider?

I am getting so many registrations from and on my forum.. all are spammers for sure.

Currently they are not posting on forum but I am sure they will do something bad in future when we will have more activity in there.

Is there any way that I can block registrations from mail.ru and gawab.com??

 

just add mail.ru and gawab.com to vb admin cp/options/user banning options/Banned Email Addresses