= P =
Noun corresp. to v. post (but note that
post can be nouned). Distinguished from a `letter' or
ordinary email 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 email; perhaps the best dividing
line is that if you don't know the names of all the potential
recipients, it is a posting.
--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.