Simple Mail Transfer Protocol extension for Message Transfer Priorities
draft-melnikov-smtp-priority-14

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Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Standards Track                             K. Carlberg
Expires: November 25, 2012                                           G11
                                                            May 24, 2012

Simple Mail Transfer Protocol extension for Message Transfer Priorities
                    draft-melnikov-smtp-priority-14

Abstract

   This memo defines an extension to the SMTP (Simple Mail Transfer
   Protocol) service whereby messages are sent with a priority to enable
   receivers to take this into account for onward processing, with the
   general goal of processing and/or transferring higher priority
   messages first.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on November 25, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as

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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  Definition of the Priority SMTP Extension  . . . . . . . . . .  3
   4.  Handling of messages received via SMTP . . . . . . . . . . . .  4
     4.1.  Handling of the MT-PRIORITY parameter by the receiving
           SMTP server  . . . . . . . . . . . . . . . . . . . . . . .  4
     4.2.  Relay of messages to other conforming SMTP servers . . . .  5
     4.3.  Relay of messages to non-conforming SMTP servers . . . . .  6
     4.4.  Mailing lists and Aliases  . . . . . . . . . . . . . . . .  6
     4.5.  Gatewaying a message into a foreign environment  . . . . .  6
     4.6.  Interaction with DSN SMTP Extension  . . . . . . . . . . .  6
   5.  The Priority Service Extension . . . . . . . . . . . . . . . .  7
     5.1.  Expedited Transfer . . . . . . . . . . . . . . . . . . . .  8
     5.2.  Timely Delivery  . . . . . . . . . . . . . . . . . . . . .  9
   6.  Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
   7.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  Deployment Considerations  . . . . . . . . . . . . . . . . . . 10
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
   10. Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 13
     11.2. Informative References . . . . . . . . . . . . . . . . . . 14
   Appendix A.  Mapping of MT-PRIORITY parameter values for
                Military Messaging  . . . . . . . . . . . . . . . . . 15
   Appendix B.  Mapping of MT-PRIORITY parameter values for MIXER . . 15
   Appendix C.  Mapping of National Security / Emergency
                Preparedness (NS/EP) Values . . . . . . . . . . . . . 16
   Appendix D.  Two possible implementation strategies  . . . . . . . 17
     D.1.  Probability  . . . . . . . . . . . . . . . . . . . . . . . 17
     D.2.  Preemption of sessions or transactions . . . . . . . . . . 17
     D.3.  Resource Allocation Models . . . . . . . . . . . . . . . . 18
   Appendix E.  Acknowledgements  . . . . . . . . . . . . . . . . . . 18

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1.  Introduction

   Where resources for switching or transfer of messages are constrained