Electronic mail is one of the most used and abused service in today communication. While many efforts have been made to fight e-mail abuses, no effective solution has yet been developed. Furthermore new technologies (e.g. wireless roaming) and new user needs (e.g. mobility) completely break the existing e-mail authentication techniques based on network topology. In this paper we present the E-Mail Policy Enforcer system (EMPE) which provides a method to cryptographically bind the identity of the original sender of an e-mail to the message body by combining digital signatures and transport level authentication data.