What e-mail/message did you accidentally send to/receive from the wrong person, and regretted it immediately?

I'll start off with a quick one. A few years ago, I was subscribed to the Qdoba e-mail list for coupons and deals and such. When I received this e-mail from them, I realized that they had made a huge mistake. Clearly, I wasn't an employee, and although not particularly awful, the stinky brown bag sort of took care of my appetite for the time being.

Later that same day, I received another e-mail from Qdoba. A very clear and understood apology for the bad PR mistake they made. Except it wasn't.

Reddit, what messages have you accidentally sent or received that couldn't have had a worse audience?