I like to think that I did what most people would do in this situation; I took a quick look,realized that it was not meant for me, and promptly filed it in the trash because mistakes happen.
Then the early shift arrived at the head office, and the first reply showed up. It was somebody who hit Reply All and said, "I just want you to know that I got this in error, and I have deleted the message."
Fair enough. IMO he did not need to do a reply to all for that, but this should have been the end of it, right?
"I deleted it too."
This went on for fourteen replies before one of our superintendents out east jumped in and said, "PLEASE STOP REPLYING TO ALL WITH THESE INANE MESSAGES."
Whether it was because all of the really stupid people had finished checking their messages, or that they took his words to heart, this stemmed the flow of the messages...
...until the next shift came in to work an hour later and they started up again.
I think the "Reply All" button should pop up a disclaimer that they have to click away - something like, "Selecting this option may disqualify you from any computer-related jobs after this message goes out. Are you sure you want to reply to ALL?"