We're a cryptocurrency gambling site. The typical high roller signs up using a throwaway email address and uses TOR or VPN. They deposit, play and withdraw and then never use the account again. Sending people an email asking for information is not something that happens in this industry.

Edit: I forgot to also point out a lot of our older accounts don't even have an email address as it wasn't required for the first few years and accounts were only created by BTC address.