Cut a mail provider from registering
I know the possibility of banning incoming spam users based on their IP, but can I ban also those using a specific provider? Nine out of ten use a specific mail provider (example: gmail, yahoo etc.) which is not used in my country at all, so I could easily send them away, as I maintain a native language wiki...
Yes, I know: They can always change the provider they use, but that would be a nuisance for them, no?