Some confusion creeping in here. There is a difference between a top level domain and a domain name.

Leeneia, you're slightly confused about the principles of domain names and whatnot. It doesn't really matter. The main point to realise is that blocking anythign from sending you email is in the long term pointless because anyone can send you an email claiming to come from any address.

You can do more sophisticated filtering, but you would be much better off finding another way of doing this. Again, most people are better off with Gmail than trying to fix their own problems.