Legal Question in Civil Litigation in California

Without answering your legal question, do you really want to deal with all of these threats of potential litigation, which erupt into actual litigation? Save yourself the headache and don't show her emails to the other parents. Litigation is extremely expensive even if she has no claim because of the cost of defense. Take my advice and just drop it. Not because she's right but because you'll be happier this way and more at peace.

You could get a restraining order, but the best thing to do if you don't want someone to send you harassing e-mails is to have them blocked through your e-mail service provider.