Penal Code section 653m deals with annoying and harassing communications. The messages do not HAVE to be threatening, just repeated and unwanted.
653m. (a) Every person who, with intent to annoy, telephones or
makes contact by means of an electronic communication device with
another and addresses to or about the other person any obscene
language or addresses to the other person any threat to inflict
injury to the person or property of the person addressed or any
member of his or her family, is guilty of a misdemeanor. Nothing in
this subdivision shall apply to telephone calls or electronic
contacts made in good faith.
If it is a single e-mail, and you did not make any threats to harm him or damage his reputation, then you should be okay. If it was merely a "settle up or we're going to court", then that should be lawful ... provided it was not repeated after you were told to leave him alone.
All because the police took a report and sent it to the DA does not mean that the DA will file anything. In some agencies, the police will send most any complaint to the DA. That way, the DA can be the guy who rejects the charges rather than have the police say there is not sufficient evidence to make the charge. So, try not to worry unless the DA pursues charges and you are either arrested or a summons is issued. It might benefit you to engage an attorney ahead of time, just in case. The attorney might be able to resolve the matter with a single phone call.
In some counties - such as mine - the DA will not file until after a restraining order prohibiting communication has been issued. If that's the case, you may find yourself subject to a no contact civil harassment restraining order which could be VERY inconvenient.
For now, do not communicate with this person again.
- Carl
