letterbomb

1. n. A piece of email containing live data intended to do nefarious things
to the recipient's machine or terminal. It used to be possible, for example,
to sends that would lock up some specific kinds of terminals when they are
viewed, so thoroughly that the user must cycle power (see cycle , sense 3)
to unwedge them. Under Unix, a  can also try to get part of its contents
interpreted as a shell command to the mailer. The results of this could
range from silly to tragic; fortunately it has been some years since any of
the standard Unix/Internet mail software was vulnerable to such an attack
(though, as the Melissa virus attack demonstrated in early 1999, Microsoft
systems can have serious problems). See also Trojan horse ; compare
nastygram. 2. Loosely, a mailbomb.