posting
A message sent to a {newsgroup} or {mailing list} (may also be
called "a post") or the act of sending it. Distinguished from
a "letter" or ordinary {electronic mail} message by the fact
that it is broadcast rather than point-to-point. It is not
clear whether messages sent to a small mailing list are
postings or e-mail; perhaps the best dividing line is that if
you don't know the names of all the potential recipients, it
is a posting.
[{Jargon File}]