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 send s 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.