Spam affiliates requests

Can any one give me advise on how to stop spam affiliates? Since installing the plug in, and even before the page was actually published and I was still working on it. i am getting nothing but spam affiliates requests. You know, the dodgy names and email addresses and when doing a google search , the names are in spam data bases. I would like to know if there is any way to completely ban domain name or similar from even registering with the affiliates program.
Thanks