Death by bcc
(Metaphorical) Death by bcc is the ultimate of all e-mail deaths. It ranks at the very top, above the basic e-mail blunder, and above the dreaded "reply-all".
For those that are too sensible to have fallen foul of these errors, let's kick off with a baseline example of death by "reply-all": You get an e-mail, from a friend, to a group of your friends, inviting you to go go-kart racing. You want to go, but you're worried one of your friends (cc'd on the list) may not be able to join because their head is too big to wear a helmet [Note: I may or may not have been that friend]. Moments later, after you have pressed the send button (and after the 10 seconds to "undo send" have elapsed on gmail) you realise you pressed "reply-all".....
Death by "bcc" is sometimes just a compounded version of death by "reply-all". Imagine the same scenario as described above, but where you, initially, were bcc'd while everyone else was cc'd. Now, not only are you replying all, telling them someone has a big head; you are hurling an insult that is coming completely out of nowhere.....
For the record, who ever the person is who used bcc, should be responsible for at least 100% of the blame if the situation escalates into the dreaded "bcc-followed-by-the-dreaded-reply-all".
I don't usually have morals of the story, but here is the moral of this story: Don't use bcc. Ever. Either leave the person off, or else do them a favour and upgrade them (or downgrade them, depending on the case) to a standard, straightforward, tried and tested "carbon copy" or "cc".
I don't advocate having the death penalty, but if one were to optimise for sadism, I would recommend death by bcc.