block a certain email for registering, but allow to use after

[doug97gxe]

A fellow admin from another board asked me to look into this, however i searched here and couldn't find anything. Anyone have an idea? Thanks

I want to block people from registering with free emails, but be able to change to another one later if they want. Basically if someone uses hotmail because they can get it anywhere, that is fine with me, but I would like them to have to originally register with a non-free email.