A more thorough explanation:

The CAN-SPAM Act of 2003 is a law that sets rules for commercial email. Commercial email is any email that promotes a product or service. The law says that commercial email must follow certain rules to be legal.

Here are the main rules that commercial email must follow:

1. The email header must not have false or misleading information.
2. The subject line must not be deceptive.
3. The email must clearly say that it is an advertisement or solicitation.
4. The email must have a way for the recipient to opt-out of future emails.
5. The email must include a clear notice of how to opt-out.
6. The sender must not send any more emails to someone who has opted-out.
7. The email must have a valid physical address for the sender.

If a sender breaks any of these rules, they can be punished by the Federal Trade Commission or other government agencies.

It's important to note that the CAN-SPAM Act only applies to commercial email, not non-commercial bulk email.

Here's an example of how the CAN-SPAM Act works:

Bob runs a company that sells vitamins. He sends an email to his customers promoting a new vitamin product. The email header says it's from Bob's company, and the subject line says "New Vitamin Product - Get Yours Today!" The email clearly says it's an advertisement for the new product, and it includes a way for customers to opt-out of future emails. The email also has Bob's company's physical address at the bottom.

This email follows all the rules of the CAN-SPAM Act, so it's legal.