Simple Mail Transfer Protocol (SMTP) Service Extension for Delivery Status Notifications (DSNs)
RFC 3461

Network Working Group                                           K. Moore
Request for Comments: 3461                       University of Tennessee
Obsoletes 1891                                              January 2003
Category: Standards Track

         Simple Mail Transfer Protocol (SMTP) Service Extension
                for Delivery Status Notifications (DSNs)

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This memo defines an extension to the Simple Mail Transfer Protocol
   (SMTP) service, which allows an SMTP client to specify (a) that
   Delivery Status Notifications (DSNs) should be generated under
   certain conditions, (b) whether such notifications should return the
   contents of the message, and (c) additional information, to be
   returned with a DSN, that allows the sender to identify both the
   recipient(s) for which the DSN was issued, and the transaction in
   which the original message was sent.

Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14, RFC 2119 [7].

Table of Contents

   1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. Framework for the Delivery Status Notification Extension . . .  4
   3. The Delivery Status Notification service extension . . . . . .  5
   4. Additional parameters for RCPT and MAIL commands . . . . . . .  6
   4.1 The NOTIFY parameter of the ESMTP RCPT command. . . . . . . .  7
   4.2 The ORCPT parameter to the ESMTP RCPT command . . . . . . . .  8
   4.3 The RET parameter of the ESMTP MAIL command . . . . . . . . .  9
   4.4 The ENVID parameter to the ESMTP MAIL command . . . . . . . .  9

Moore                       Standards Track                     [Page 1]
RFC 3461                   SMTP DSN Extension               January 2003

   4.5 Restrictions on the use of Delivery Status Notification
       parameters. . . . . . . . . . . . . . . . . . . . . . . . . . 10
   5. Conformance requirements . . . . . . . . . . . . . . . . . . . 10
   5.1 SMTP protocol interactions. . . . . . . . . . . . . . . . . . 11
   5.2 Handling of messages received via SMTP. . . . . . . . . . . . 11
   5.2.1 Relay of messages to other conforming SMTP servers. . . . . 12
   5.2.2 Relay of messages to non-conforming SMTP servers. . . . . . 13
   5.2.3 Local delivery of messages. . . . . . . . . . . . . . . . . 14
   5.2.4 Gatewaying a message into a foreign environment . . . . . . 14
   5.2.5 Delays in delivery. . . . . . . . . . . . . . . . . . . . . 15
   5.2.6 Failure of a conforming MTA to deliver a message. . . . . . 16
   5.2.7 Forwarding, aliases, and mailing lists. . . . . . . . . . . 16
   5.2.7.1 mailing lists . . . . . . . . . . . . . . . . . . . . . . 17
   5.2.7.2 single-recipient aliases. . . . . . . . . . . . . . . . . 18
   5.2.7.3 multiple-recipient aliases. . . . . . . . . . . . . . . . 18
   5.2.7.4 confidential forwarding addresses . . . . . . . . . . . . 18
   5.2.8 DSNs describing delivery to multiple recipients . . . . . . 19
   5.3 Handling of messages from other sources . . . . . . . . . . . 19
   5.4 Implementation limits . . . . . . . . . . . . . . . . . . . . 19
   6. Format of delivery notifications . . . . . . . . . . . . . . . 20
   6.1 SMTP Envelope to be used with delivery status
       notifications . . . . . . . . . . . . . . . . . . . . . . . . 20
   6.2 Contents of the DSN . . . . . . . . . . . . . . . . . . . . . 20
   6.3 Message/delivery-status fields. . . . . . . . . . . . . . . . 21
   7. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . 22
   8. Security Considerations. . . . . . . . . . . . . . . . . . . . 22
   9. Appendix - Type-Name Definitions . . . . . . . . . . . . . . . 24
   9.1 "rfc822" address-type . . . . . . . . . . . . . . . . . . . . 24
   9.2 "smtp" diagnostic-type. . . . . . . . . . . . . . . . . . . . 24
   9.3 "dns" MTA-name-type . . . . . . . . . . . . . . . . . . . . . 25
   10. Appendix - Example. . . . . . . . . . . . . . . . . . . . . . 26
   10.1 Submission . . . . . . . . . . . . . . . . . . . . . . . . . 27
   10.2 Relay to Example.COM . . . . . . . . . . . . . . . . . . . . 28
   10.3 Relay to Ivory.EDU . . . . . . . . . . . . . . . . . . . . . 29