sorry, missed the point that he's your ex (doh)! Second Coppertop's point but you need some evidence to demonstrate that it wasn't you sending these replies ? you need to protect yourself here. I do really, really think you need some legal advice ? it could get very nasty. Your boss may not take the email content seriously, but once company procedures are invoked, things can get really out of hand, even for innocent parties. You're in a very difficult position here ? you do need to alert your bosses to this but it does place you at risk.