CAN-SPAM Act
Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003. A U.S. law regulating commercial email. This anti-spam legislation requires that each email should contain: a legitimate header, a valid “From” address, a straightforward “Subject” line, an unsubscribe/opt-out link and/or instructions and a physical address. It also states that all unsubscribes must be processed within ten days of receipt.