If you are using an email to sign up and verifying that user actually controls email as is normal presumably they could look up the bond with your email. Essen

If you are using an email to sign up and verifying that user actually controls email as is normal presumably they could look up the bond with your email. Essentially registrar and major sites would coordinate to get bot accounts revoked your registrar wouldn't want to cancel user accounts erroneously. In most cases logically the registrar could be your email provider which would just be selling a verified email address but a third party could offer the same thing.