Check users email on registration

[Ren]

Hello,

Let me explain what I desire :alien:
I don't allow members to use Hotmail or Yahoo account's to sign up for my board because it seems like 99% of those people love to cause trouble on the message boards .

I get tired of manually checking and deleting people that can't read what I have added to the email registration field , and was wondering if it would be possiable to have it check and give a error message if someone used a forbidden email to sign up?

Thank's for Listening , Ren