Post Office Protocol - Version 3 (RFC1460)
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
On certain types of smaller nodes in the Internet it is often impractical to maintain a message transport system (MTS). For example, a workstation may not have sufficient resources (cycles, disk space) in order to permit a SMTP server [RFC821] and associated local mail delivery system to be kept resident and continuously running.
Network Working Group M. Rose
Request for Comments: 1460 Dover Beach Consulting, Inc.
Obsoletes: 1225 June 1993
Post Office Protocol - Version 3
Status of this Memo
This RFC specifies an IAB standards track protocol for the Internet
community, and requests discussion and suggestions for improvements.
Please refer to the current edition of the "IAB Official Protocol
Standards" for the standardization state and status of this protocol.
Distribution of this memo is unlimited.
This memo is a revision to RFC 1225, a Draft Standard. It makes the
following changes from that document:
- the RPOP facility is removed;
- the optional APOP facility is added (which is in interoperable,
operational use in at least three implementations);
- a typo was corrected with respect to the interaction of LAST
- section numbers were added; and,
- an acknowledgements section was added.
On certain types of smaller nodes in the Internet it is often
impractical to maintain a message transport system (MTS). For
example, a workstation may not have sufficient resources (cycles,
disk space) in order to permit a SMTP server [RFC821] and associated
local mail delivery system to be kept resident and continuously
Similarly, it may be expensive (or impossible) to keep a personal
computer interconnected to an IP-style network for long amounts of
time (the node is lacking the resource known as "connectivity").
Despite this, it is often very useful to be able to manage mail on
these smaller nodes, and they often support a user agent (UA) to aid
the tasks of mail handling. To solve this problem, a node which can
support an MTS entity offers a maildrop service to these less endowed
nodes. The Post Office Protocol - Version 3 (POP3) is intended to
permit a workstation to dynamically access a maildrop on a server
host in a useful fashion. Usually, this means that the POP3 is used
to allow a workstation to retrieve mail that the server is holding
For the remainder of this memo, the term "client host" refers to a
host making use of the POP3 service, while the term "server host"
refers to a host which offers the POP3 service.
2. A Short Digression
This memo does not specify how a client host enters mail into the
transport system, although a method consistent with the philosophy of
this memo is presented here:
When the user agent on a client host wishes to enter a message
into the transport system, it establishes an SMTP connection to
its relay host (this relay host could be, but need not be, the
POP3 server host for the client host).
If this method is followed, then the client host appears to the MTS
as a user agent, and should NOT be regarded as a "trusted" MTS entity
in any sense...