Simple Mail Transfer Protocol extension for Message Transfer Priorities
draft-melnikov-smtp-priority-11

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Last updated 2012-04-25
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Network Working Group                                        A. Melnikov
Internet-Draft                                                 Isode Ltd
Intended status: Standards Track                             K. Carlberg
Expires: October 27, 2012                                            G11
                                                          April 25, 2012

Simple Mail Transfer Protocol extension for Message Transfer Priorities
                    draft-melnikov-smtp-priority-11

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

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   This Internet-Draft will expire on October 27, 2012.

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   Copyright (c) 2012 IETF Trust and the persons identified as the
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Melnikov & Carlberg     Expires October 27, 2012                [Page 1]
Internet-Draft  Message Transfer Priority SMTP Extension      April 2012

   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  . . . . . . . . . .  4
   4.  Handling of messages received via SMTP . . . . . . . . . . . .  4
     4.1.  Handling of the MT-PRIORITY parameter by the receiving
           SMTP server  . . . . . . . . . . . . . . . . . . . . . . .  4
     4.2.  Determining priority of a message  . . . . . . . . . . . .  5
     4.3.  Relay of messages to other conforming SMTP servers . . . .  6
     4.4.  Relay of messages to non-conforming SMTP servers . . . . .  6
     4.5.  Mailing lists and Aliases  . . . . . . . . . . . . . . . .  7
     4.6.  Gatewaying a message into a foreign environment  . . . . .  7
     4.7.  Interaction with DSN SMTP Extension  . . . . . . . . . . .  7
   5.  The Priority Service Extension . . . . . . . . . . . . . . . .  7
     5.1.  Expedited Transfer . . . . . . . . . . . . . . . . . . . .  9
     5.2.  Timely Delivery  . . . . . . . . . . . . . . . . . . . . . 10
   6.  Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   7.  Header field: MT-Priority  . . . . . . . . . . . . . . . . . . 10
   8.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
   9.  Deployment Considerations  . . . . . . . . . . . . . . . . . . 12
   10. IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   11. Security Considerations  . . . . . . . . . . . . . . . . . . . 14
     11.1. Modification of MT-Priority header field and DKIM  . . . . 15
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 15
     12.2. Informative References . . . . . . . . . . . . . . . . . . 16
   Appendix A.  Mapping of MT-PRIORITY parameter values for
                Military Messaging  . . . . . . . . . . . . . . . . . 17
   Appendix B.  Mapping of MT-PRIORITY parameter values for MIXER . . 18
   Appendix C.  Mapping of National Security / Emergency
                Preparedness (NS/EP) Values . . . . . . . . . . . . . 18
   Appendix D.  Two possible implementation strategies  . . . . . . . 19
     D.1.  Probability  . . . . . . . . . . . . . . . . . . . . . . . 19
     D.2.  Preemption of sessions or transactions . . . . . . . . . . 19
   Appendix E.  Resource Allocation Models  . . . . . . . . . . . . . 20
   Appendix F.  Acknowledgements  . . . . . . . . . . . . . . . . . . 20
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