You can restrict fake email or IP or auto disable an account based on number of report that account received.
Navigation Path: Login as admin-> go to admincp-> general configuration -> Spam & Banning Tools
IP address ban: you can ban any IP that you want by adding them into the text box
Email address ban: you can ban list of email that you don’t want them to sign up to your site
Report system provides you option to auto ban a member if they get xx report from existing member. See below screenshot
