Many years ago we had one too. It was very hot in the first day or two, but like with a forest fire, you had new outbreaks when people returned from vacation an

Many years ago we had one too. It was very hot in the first day or two, but like with a forest fire, you had new outbreaks when people returned from vacation and before having read any other replies, replied to all "unsubscribe" or "why am I getting this?". Which prompted again replies, not to reply to all and so on... Took about two weeks to get completely stopped. It seems, after that, mail to all in the company was effectively eliminated except for a whitelist of accounts.