I was there when this was happening and realized exactly what was going on at the time. Still, it was very very hard not to respond with a 'Stop replying all' type message. There is something about these things that makes it hard to just sit it out and shut up (at least for me).

The list had a broad section of the company. It wasn't surprising to see some of the less computer savvy users responding. I was surprised though when I saw engineers down the hall responding.