A more thorough explanation:

The CAN-SPAM Act of 2003 is a law that regulates commercial email messages. Section 4 of this law makes certain spam-related activities a misdemeanor criminal offense. This means that people who engage in these activities can be charged with a crime and face penalties such as fines or imprisonment.

One example of a spam-related activity that can result in criminal liability is when a spammer hacks into someone else's email account and uses it to send out spam. Another example is when a spammer uses fraudulent means to gain access to someone else's email account and sends out spam from that account.

For instance, if a person hacks into their friend's email account and sends out spam emails to promote a product, they could be charged with a crime under the CAN-SPAM Act of 2003.

In 2007 and 2009, the constitutionality of these criminal prohibitions was challenged in court, but the courts upheld them as constitutional.

The United States Sentencing Commission provides guidelines for enforcing these criminal prohibitions.