A: Early in law school we learned that any bargain for consideration can be legally binding, meaning anything even written on a cocktail napkin can be binding if it contains the elements necessary to deem it a contract. Although I am answering this as a hypothetical and not as your attorney it is very possible for an agreement to be deemed legally binding when done via email if it can meet the threshold of being a contract. The basic elements for a contract or legally binding agreement are offer and acceptance, adequate consideration, capacity and legality of the contract. If an email contains all those elements it can be an agreement that was made through the course of the communication. I would certainly recommend speaking with your divorce attorney or a family law attorney licensed in your state if you are concerned about any possible liability.
*The answer above does not constitute legal advice, nor create an attorney-client relationship.*