Short description of Mail UnKnown Anti-Spam 1.532: Stop spam with Mail UnKnown. Mail UnKnown does NOT use spam filters to guess what’s spam and what’s not. It uses a Verify then Validate method giving you full control of the emails you receive. All incoming emails are put on hold until the sender of the email is first verified. After they are, you have the option to validate them as an email sender you want to receive emails from.