First, you should know that CAN-SPAM stands for Controlling the Assault of Non-Solicited Pornography And Marketing and it is a U.S.act that passed in 2003. This act actually covers all commercial messages and it states that the sender should always provide a visible and operable unsubscribe mechanism, but also the sender's valid physical postal address. If you would like to learn more about this act, you can easily access this business compliance guide provided by the Federal Trade Commission.