Is the email address your only lead? Most spam comes from data center IP's, Hostnames, AS Names. Since the only legit traffic coming from those is VPN's we just block any that cause a problem. We don't mind users using a VPN but we prevent registration from many of them.
Blocks have to be based on your clientele. Blocking emails this way is going to get a lot of false positives when it comes to government, military and contractors for either for example.