Internationalized Delivery Status and Disposition Notifications
RFC 5337

Network Working Group                                          C. Newman
Request for Comments: 5337                              Sun Microsystems
Updates: 3461, 3464, 3798                               A. Melnikov, Ed.
Category: Experimental                                         Isode Ltd
                                                          September 2008

    Internationalized Delivery Status and Disposition Notifications

Status of This Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Abstract

   Delivery status notifications (DSNs) are critical to the correct
   operation of an email system.  However, the existing Draft Standards
   (RFC 3461, RFC 3462, RFC 3464) are presently limited to US-ASCII text
   in the machine-readable portions of the protocol.  This specification
   adds a new address type for international email addresses so an
   original recipient address with non-US-ASCII characters can be
   correctly preserved even after downgrading.  This also provides
   updated content return media types for delivery status notifications
   and message disposition notifications to support use of the new
   address type.

   This document experimentally extends RFC 3461, RFC 3464, and RFC
   3798.

Newman & Melnikov             Experimental                      [Page 1]
RFC 5337             Internationalized DSN and MDNs       September 2008

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Conventions Used in This Document  . . . . . . . . . . . . . .  3
   3.  UTF-8 Address Type . . . . . . . . . . . . . . . . . . . . . .  3
   4.  UTF-8 Delivery Status Notifications  . . . . . . . . . . . . .  6
     4.1.  Additional Requirements on SMTP Servers  . . . . . . . . .  8
   5.  UTF-8 Message Disposition Notifications  . . . . . . . . . . .  9
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
     6.1.  UTF-8 Mail Address Type Registration . . . . . . . . . . . 10
     6.2.  Update to 'smtp' Diagnostic Type Registration  . . . . . . 11
     6.3.  message/global-headers . . . . . . . . . . . . . . . . . . 11
     6.4.  message/global-delivery-status . . . . . . . . . . . . . . 12
     6.5.  message/global-disposition-notification  . . . . . . . . . 13
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 15
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 16
   Appendix A.  Acknowledgements  . . . . . . . . . . . . . . . . . . 17

Newman & Melnikov             Experimental                      [Page 2]
RFC 5337             Internationalized DSN and MDNs       September 2008

1.  Introduction

   When an email message is transmitted using the UTF8SMTP [RFC5336]
   extension and Internationalized Email Headers [RFC5335], it is
   sometimes necessary to return that message or generate a Message
   Disposition Notification (MDN) [RFC3798].  As a message sent to
   multiple recipients can generate a status and disposition
   notification for each recipient, it is helpful if a client can
   correlate these notifications based on the recipient address it
   provided; thus, preservation of the original recipient is important.
   This specification describes how to preserve the original recipient
   and updates the MDN and DSN formats to support the new address types.

2.  Conventions Used in This Document

   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 [RFC2119].

   The formal syntax use the Augmented Backus-Naur Form (ABNF) [RFC5234]
   notation including the core rules defined in Appendix B of RFC 5234
   [RFC5234] and the UTF-8 syntax rules in Section 4 of [RFC3629].

3.  UTF-8 Address Type

   An Extensible Message Format for Delivery Status Notifications
   [RFC3464] defines the concept of an address type.  The address format
   introduced in Internationalized Email Headers [RFC5335] is a new
   address type.  The syntax for the new address type in the context of
   status notifications is specified at the end of this section.

   An SMTP [RFC2821] server that advertises both the UTF8SMTP extension
   [RFC5336] and the DSN extension [RFC3461] MUST accept a UTF-8 address