Post Office Protocol: Version 2 (RFC0937)
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2000-Oct-11
Internet Society Requests For Comment (RFCs)
M. Butler: AUTHOR [+5]
The intent of the Post Office Protocol Version 2 (POP2) 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). For further information see RFC-821  and RFC-822 .
Network Working Group M. Butler
Request for Comments: 937 J. Postel
J. K. Reynolds
Obsoletes: RFC 918 ISI
POST OFFICE PROTOCOL - VERSION 2
Status of this Memo
This RFC suggests a simple method for workstations to dynamically
access mail from a mailbox server. This RFC specifies a proposed
protocol for the ARPA-Internet community, and requests discussion and
suggestions for improvement. This memo is a revision of RFC 918.
Distribution of this memo is unlimited.
The intent of the Post Office Protocol Version 2 (POP2) 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). For further
information see RFC-821  and RFC-822 .
This protocol assumes a reliable data stream such as provided by TCP
or any similar protocol. When TCP is used, the POP2 server listens
on port 109 .
System Model and Philosophy
While we view the workstation as an Internet host in the sense that
it implements IP, we do not expect the workstation to contain the
user's mailbox. We expect the mailbox to be on a server machine.
We believe it is important for the mailbox to be on an "always up"
machine and that a workstation may be frequently powered down, or
otherwise unavailable as an SMTP server.
POP2 is designed for an environment of workstations and servers on a
low-delay, high-throughput, local networks (such as Ethernets). POP2
may be useful in other environments as well, but if the environment
is substantially different, a different division of labor between the
client and server may be appropriate, and a different protocol
Suppose the user's real name is John Smith, the user's machine is
called FIDO, and that the mailbox server is called DOG-HOUSE. Then
RFC 937 February 1985
Post Office Protocol
we expect the user's mail to be addressed to JSmith@DOG-HOUSE.ARPA
That is, the destination of the mail is the mailbox on the server
machine. The POP2 protocol and the workstation are merely a
mechanism for viewing the messages in the mailbox.
The user is not tied to any particular workstation for accessing his
mail. The workstation does not appear as any part of the mailbox
This is a very simple protocol. This is not a user interface. We
expect that there is a program in the workstation that is friendly to
the user. This protocol is not ...