In 2003, the Controlling the Assault of Non-Solicited Pornography And Marketing Act (CAN-SPAM Act) became law. It was a big step toward cleaning up the "Wild West" of email marketing.
Continuing that clean-up, earlier this year the Federal Trade Commission (FTC) modified the act, allowing email marketers to use their "accurately registered post office box or private mailbox" instead of a "valid physical postal address" in their emails.
The CAN-SPAM act, however, has not changed much over the years and should be followed not only because it is the law but also because it will make you a better email marketer.
How Your Email Service Provider (ESP) Should Help
Reputable ESPs make it very easy to comply with key CAN-SPAM provisions.
The law requires that your subscribers have a way to unsubscribe from your emails. Most ESPs help you comply by placing an unsubscribe link at the bottom of each email.
The law requires that you use a valid From email address. Some ESPs automatically send a validation email to the From email address or addresses you choose. This prevents email marketers from using an invalid email From address.
In addition, as noted earlier, the law requires that you include a postal box or physical mailing address in each commercial email you send.