Legal Question in Technology Law in California

If a court still has jurisdiction, the judge could issue an order restricting or cutting off his right to communicate. I don't know the particulars since this is basically a Family Law issue and I don't practice in that area regularly. Even if the court doesn't have jurisdiction over the divorce proceeding at this time, a court can always be asked to issue a restraining order. The procedure is pretty simple, she shouldn't need a lawyer, and the court clerk can provide the application form.

This is called stalking, and aside from restraining orders she can sue him or call the police.

I agree with Mr. Whipple and Mr. Stone that restraining order is the right remedy to seek, but it is not clear from your question that such an order would be appropriate. If your daughter and her husband are both pro per in the divorce court, the only way he can even discuss the case with her is by contacting her directly. If they have children, he also has to communicate with her about them. Their divorce may involve property issues, requests for spousal support, etc. It's not hard to imagine valid reasons for the husband to send her numerous emails.

Sending 16 messages per day does sound like a lot, but all you said was that he has sent "up to" 16 messages in a 24-hour period. Evidently he sends fewer than 16 on average. For all we know, on a typical day he may send a lot fewer.

The fact that your daughter is distressed about these emails matters, but it is not enough by itself to justify a restraining order. The court will need to evaluate the reasonableness of her reaction, as well as the reasonableness of her husband's conduct. You have not given us enough information to make those evaluations, so there is no way to say whether the court should issue a restraining order.