RFC 1339 (rfc1339) - Page 1 of 6
Remote Mail Checking Protocol
Alternative Format: Original Text Document
Network Working Group S. Dorner
Request for Comments: 1339 P. Resnick
U. of Illinois at Urbana-Champaign
June 1992
Remote Mail Checking Protocol
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. Discussion and suggestions for improvement are requested.
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.
Abstract
This RFC defines a protocol to provide a mail checking service to be
used between a client and server pair. Typically, a small program on
a client workstation would use the protocol to query a server in
order to find out whether new mail has arrived for a specified user.
Intent
This RFC defines a simple, low-overhead protocol for checking the
status of a maildrop on a host. It is primarily intended for use in
adjunct with "remote mail" servers such as those implementing the
Post Office Protocol (RFC 1225). Remote mail clients must poll their
servers to discover the arrival of mail. Using one of the remote mail
protocols for periodic checking can be quite impractical and
expensive for the server since either a constant connection between
client and server must be maintained or repeated and expensive user
validations must be done. Furthermore, users on less capable
computers may not wish to devote the memory required to have a full
implementation of the client polling for mail. Thus, we feel that an
easy to implement and inexpensive to use polling scheme would be of
benefit both to mail servers and their clients.
Protocol Overview
To avoid connection overhead, the Remote Mail Checking Protocol is
based on the User Datagram Protocol (UDP), using UDP port 50 decimal
(62 octal) for the server. The protocol provides for both non-
authenticated and authenticated polling. Non-authenticated polling is
simplest for both client and server. Authenticated polling provides a
small increment of privacy, at the cost of more complexity in both
client and server (but still far less than polling with one of the
Dorner & Resnick