Just yesterday a friend of mine wrote his ex-wife an email where they were arguing back and forth about a kid issue.
The ex-wife topped his email with some sharp criticism of him, meaning to fwd it to her current husband. She hit reply instead and sent it back to my friend, her ex-husband.
Whoops there. Then she was dumb enough to send another email right on top of that telling him to disregard her previous email as it was meant for her current husband.