BanditFlyer made the same point I was trying to make. It's entirely possible for someone (anyone) to get their password and username and send an email from that account, so there really is no way to prove, in a court of law, who sent it. The others made a good point too. Relationships are dependent on trust; without it, they won't work. So if you're that suspicious of him, then you have far greater problems than figuring out who sent an email message.