Working at a hedge fund with multiple locations, the founder insisted that mail to “staff” would reach everyone at the local office and mail to “all” would reach everyone.

One afternoon (in the middle of the trading day), we got a weird email with an empty body and a bunch of nonsense email addresses. Turns out some poor trader wrote an online dating email (which happened to include the word all) pasted/wrote the mail in the cc line, resulting in all of us learning that he thought “you don’t seem like all the other girls”, which was sent to you@, don’t@, seem@, and the dreaded all@.