RFC 1339 (rfc1339) - Page 1 of 6

Remote Mail Checking Protocol

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