We were getting a lot of fraud orders with public emails (gmail, yahoo, etc). All registration with public email service are blocked.
You can block registration from certain domain too. Please download our plugin 🙂
Download & Install
1. Download file from http://cdn.hostbillapp.com/addons/regblacklist/regblacklist.zip
2. Copy zip archive into HostBill directory: /includes/modules/Other
3. Extract all files
4. Activate in HostBill – http://cdn.hostbillapp.com/addons/regblacklist/addon_registration_blacklist.swf