See Also: Simple Mail Transfer Protocol (SMTP)
The text-based protocol used to send and retrieve Internet (see Internet - Overview) e-mail messages. Unlike SMTP, which is used primarily to transfer mail
messages between mail servers, POP provides a way for mail programs to interact with
the virtual mailboxes in which messages wait until they are sent or retrieved.
POP comes in two flavors: POP2 and POP3. The two are related in name only and
are not compatible.