"In the interest of full disclosure, this is mine:
I was working at a Fortune 50 bank as a consultant. I was due to go on vacation for a week and the company did not have webmail. I decided that I would try forwarding emails to my corporate account. (I know this was a bad idea, and probably against several corporate policies.) I set it up so that any email that came in would forward to my consulting company's account. My mistake was I also left Delivery Receipt on. This was not Microsoft, it was Lotus Notes. The system began forwarding the incoming mail to my account. But then it would get a Delivery Receipt, which in turn would be forwarded to my account, which would generate another delivery receipt, ad infinitum. When I got back from vacation they claimed I had brought down the email system for 4 hours. This incident caused the bank to stop allowing consultants to set up email rules. What's your story?"