Good to limit like this, and is why I used real name when registering. My Email is not the same though because, when purchasing, the system you use allows the Paypal email to override emails picked. Determining by email alone may prove difficult. To eliminate and track spam I have probably close to 100+ email address that all forward to my real one, so nothing online has the same email. I imagine with as cheap as domain and hosting is I'm probably not the only one to do this too.