Simple Mail Transfer Protocol extension for Message Transfer Priorities
draft-melnikov-smtp-priority-20

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Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Standards Track                             K. Carlberg
Expires: January 4, 2013                                             G11
                                                            July 3, 2012

Simple Mail Transfer Protocol extension for Message Transfer Priorities
                    draft-melnikov-smtp-priority-20

Abstract

   This memo defines an extension to the SMTP (Simple Mail Transfer
   Protocol) service whereby messages are given a label to indicate
   preferential handling, to enable mail handling nodes to take this
   into account for onward processing.

Status of This Memo

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   This Internet-Draft will expire on January 4, 2013.

Copyright Notice

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

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Melnikov & Carlberg      Expires January 4, 2013                [Page 1]
Internet-Draft  Message Transfer Priority SMTP Extension       July 2012

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  4
   3.  Definition of the Priority SMTP Extension  . . . . . . . . . .  4
   4.  Handling of messages received via SMTP . . . . . . . . . . . .  5
     4.1.  Handling of the MT-PRIORITY parameter by the receiving
           SMTP server  . . . . . . . . . . . . . . . . . . . . . . .  5
     4.2.  Relay of messages to other conforming SMTP servers . . . .  6
     4.3.  Relay of messages to non-conforming SMTP servers . . . . .  7
     4.4.  Mailing lists and Aliases  . . . . . . . . . . . . . . . .  7
     4.5.  Gatewaying a message into a foreign environment  . . . . .  7
     4.6.  Interaction with DSN SMTP Extension  . . . . . . . . . . .  7
   5.  The Priority Service Extension . . . . . . . . . . . . . . . .  8
     5.1.  Expedited Transfer . . . . . . . . . . . . . . . . . . . .  9
     5.2.  Timely Delivery  . . . . . . . . . . . . . . . . . . . . . 10
   6.  Use of MT-PRIORITY with LMTP . . . . . . . . . . . . . . . . . 10
   7.  Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   9.  Deployment Considerations  . . . . . . . . . . . . . . . . . . 14
     9.1.  Multiple MX records  . . . . . . . . . . . . . . . . . . . 14
     9.2.  Priority Assignment Policies . . . . . . . . . . . . . . . 14
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
     10.1. Requirements on Priority Assignment Policy
           registrations  . . . . . . . . . . . . . . . . . . . . . . 17
     10.2. Initial Priority Assignment Policy registrations . . . . . 18
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 19
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 19
     12.2. Informative References . . . . . . . . . . . . . . . . . . 20
   Appendix A.  Priority Assignment Policy for Military Messaging . . 21
   Appendix B.  Priority Assignment Policy for MIXER  . . . . . . . . 22
   Appendix C.  Priority Assignment Policy for National Security
                / Emergency Preparedness (NS/EP)  . . . . . . . . . . 23
   Appendix D.  Possible implementation strategies  . . . . . . . . . 24
     D.1.  Probability  . . . . . . . . . . . . . . . . . . . . . . . 25
     D.2.  Preemption of sessions or transactions . . . . . . . . . . 25
     D.3.  Resource Allocation Models . . . . . . . . . . . . . . . . 25
   Appendix E.  Background on Design Choices  . . . . . . . . . . . . 26