I work for a major airline and the same thing happened to me. I wanted to send a insulting message to one of my coworkers who didn't even know there was such a thing as messenger service but it gave me an error so I used the /? switch and one of the things mentioned was the /domain switch that I used next (my god, what was I thinking then) I knew I had made a mistake as soon as I hit enter but it was to late....
2 minutes later someone from IT came rushing over asking my coworker if he was sending messages (because his name was in the message), I told them it wasn't him and they looked at me and said: Oh no it's you again!!!! Why is it always you when stuff like this is happening???
Anyway luckily for me they smiled and went back to work, so next time I will be more carefull.
Funny thing is that my coworker never saw the message because his computer (2 desks away) was in another domain but a whole lot of other people in the building did.