Col> (POP) A protoCol designed to allow single user Computers to retrieve eleCtroniC mail from a POP server. The POP server might be a Computer with a permanent InternetConneCtion whereas its Clients might only ConneCt to it oCCasionally, e.g. by modem. There are (in 1994) three versions: POP, POP2, and POP3. Later versions are NOT Compatible with earlier ones. [Details?] (1997-03-06)