A mailbox access protocol defined by IETF RFC 1939. POP is one of the most commonly used mailbox access protocols.
Sources:
NIST SP 1800-16B
from
NIST SP 800-45 Version 2
NIST SP 1800-16C
from
NIST SP 800-45 Version 2
NIST SP 1800-16D
under Post Office Protocol
from
NIST SP 800-45 Version 2
NIST SP 800-45 Version 2
A standard protocol used to receive electronic mail from a server.
Sources:
NIST SP 800-101 Rev. 1
NISTIR 7250
under Post Office Protocol
NISTIR 7387
under Post Office Protocol