Note: This concerns e-mail that is sent nationally, giving every state the jurisdiction to prosecute the senders for what is sent to their state. Therefore, the location listed is arbitrary. Lawyers from any state may respond to say whether prosecution is possible in their state.]
In many states, there are still laws that make adultery a crime, although they are not widely enforced.
Also, there are laws that prohibit encouraging a person to commit a crime.
There is a lot of spam that tells recipients to cheat on their spouses or to do something with cheating wives.
This got me thinking:
Even in states that don't enforce their adultery laws, could they still crack down on spam by prosecuting the senders of the spam for unlawfully soliciting potential customers to commit adultery?