http://www.rfc-editor.org/rfc/rfc0918.txt
RFC 0918: Post Office Protocol, J.K. Reynolds1984-10-01T23:00:00-00:00This RFC suggests a simple method for workstations to dynamically access mail from a mailbox server. The intent of the Post Office Protocol (POP) is to allow a user's workstation to access mail from a mailbox server. It is expected that mail will be posted from the workstation to the mailbox server via the Simple Mail Transfer Protocol (SMTP). This RFC specifies a proposed protocol for the ARPA-Internet community, and requests discussion and suggestions for improvement. The status of this protocol is experimental, and this protocol is dependent upon TCP.