RFC 1427 (rfc1427) - Page 1 of 8

SMTP Service Extension for Message Size Declaration

Network Working Group                               J. Klensin, WG Chair
Request for Comments: 1427                     United Nations University
                                                        N. Freed, Editor
                                            Innosoft International, Inc.
                                                                K. Moore
                                                 University of Tennessee
                                                           February 1993


                         SMTP Service Extension
                      for Message Size Declaration

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.

1.  Abstract

   This memo defines an extension to the SMTP service whereby an SMTP
   client and server may interact to give the server an opportunity to
   decline to accept a message (perhaps temporarily) based on the
   client's estimate of the message size.

2.  Introduction

   The MIME extensions to the Internet message protocol provide for the
   transmission of many kinds of data which were previously unsupported
   in Internet mail.  One expected result of the use of MIME is that
   SMTP will be expected to carry a much wider range of message sizes
   than was previously the case.  This has an impact on the amount of
   resources (e.g., disk space) required by a system acting as a server.

   This memo uses the mechanism defined in [5] to define extensions to
   the SMTP service whereby a client ("sender-SMTP") may declare the
   size of a particular message to a server ("receiver-SMTP"), after
   which the server may indicate to the client that it is or is not
   willing to accept the message based on the declared message size and
   whereby a server ("receiver-SMTP") may declare the maximum message
   size it is willing to accept to a client ("sender-SMTP").

3.  Framework for the Size Declaration Extension

   The following service extension is therefore defined:




Klensin, Freed & Moore