This invention provides a method of blocking unwanted emails, yet provides the flexibility to permit the recipient to receive emails from new senders as desired. This invention provides a firewall with a list of approved senders as described above. In addition, however, the method of this invention permits...http://www.google.ca/patents/US20040243847?utm_source=gb-gplus-sharePatent US20040243847 - Method for rejecting SPAM email and for authenticating source addresses in email servers
