The Multipart/Report Media Type for the Reporting of Mail System Administrative Messages
RFC 6522

Internet Engineering Task Force (IETF)                 M. Kucherawy, Ed.
Request for Comments: 6522                                     Cloudmark
STD: 73                                                     January 2012
Obsoletes: 3462
Category: Standards Track
ISSN: 2070-1721

                  The Multipart/Report Media Type for
          the Reporting of Mail System Administrative Messages

Abstract

   The multipart/report Multipurpose Internet Mail Extensions (MIME)
   media type is a general "family" or "container" type for electronic
   mail reports of any kind.  Although this memo defines only the use of
   the multipart/report media type with respect to delivery status
   reports, mail processing programs will benefit if a single media type
   is used for all kinds of reports.

   This memo obsoletes "The Multipart/Report Content Type for the
   Reporting of Mail System Administrative Messages", RFC 3462, and
   marks RFC 3462 and its predecessor as "Historic".

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6522.

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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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   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................3
   2. Document Conventions ............................................3
   3. The Multipart/Report Media Type .................................3
   4. The text/rfc822-headers Media Type ..............................5
   5. Registering New Report Types ....................................7
   6. IANA Considerations .............................................7
   7. Security Considerations .........................................7
   8. References ......................................................7
      8.1. Normative References .......................................7
      8.2. Informative References .....................................8
   Appendix A.  Acknowledgements ......................................9

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1.  Introduction

   [OLD-REPORT] and its antecedent declared the multipart/report media
   type for use within the [MIME] construct to create a container for
   mail system administrative reports of various kinds.

   Practical experience has shown that the general requirement of having
   that media type constrained to be used only as the outermost MIME
   type of a message is overly restrictive and limits such things as the
   transmission of multiple administrative reports within a single
   overall message container.  In particular, it prevents one from
   forwarding a report as part of another multipart MIME message.

   This memo removes that constraint.  No other changes apart from some
   editorial ones are made.  Other memos might update other documents to
   establish or clarify the constraints on use of multipart/report in
   contexts where such are needed.

   This memo obsoletes RFC 3462.  RFC 3462 and its predecessor, RFC
   1892, have been marked as "Historic".

2.  Document Conventions

   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 [KEYWORDS].

3.  The Multipart/Report Media Type

   The multipart/report MIME media type is a general "family" or
   "container" type for electronic mail reports of any kind.  Although
   this memo defines only the use of the multipart/report media type
   with respect to delivery status reports, mail processing programs
   will benefit if a single media type is used for all kinds of reports.

   Per [MIME-REG], the multipart/report media type is defined as
   follows:

   Type name:  multipart

   Subtype name:  report

   Required parameters:  boundary, report-type

   Optional parameters:  none

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   Encoding considerations:  7bit should always be adequate

   Security considerations:  see Section 7 of [RFC6522]

   Interoperability considerations:  see Section 1 of [RFC6522]

   Published specification:  [RFC6522]

   Applications that use this media type:  Mail Transfer Agents, Mail
      User Agents, spam detection and reporting modules, virus detection
      modules, and message authentication modules.

   Additional information:

      Magic number(s):  N/A

      File extension(s):  N/A

      Macintosh file type code(s):  N/A

   Person and email address to contact for further information:  Murray
      S. Kucherawy <msk@cloudmark.com>

   Intended usage:  common

   Restrictions on usage:  none; however, other applications that
      register report types may establish such restrictions.

   Author:  Murray S. Kucherawy <msk@cloudmark.com>

   Change controller:  IESG

   The syntax of multipart/report is identical to the multipart/mixed
   content type defined in [MIME].  The report-type parameter identifies
   the type of report.  The parameter is the MIME subtype of the second
   body part of the multipart/report.  (See Section 5.)

   The multipart/report media type contains either two or three sub-
   parts, in the following order:

   1.  (REQUIRED) The first body part contains a human-readable message.
       The purpose of this message is to provide an easily understood
       description of the condition(s) that caused the report to be
       generated, for a human reader who might not have a user agent
       capable of interpreting the second section of the multipart/
       report.  The text in the first section can use any IANA-
       registered MIME media type, charset, or language.  Where a
       description of the error is desired in several languages or

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       several media, a multipart/alternative construct MAY be used.
       This body part MAY also be used to send detailed information that
       cannot be easily formatted into the second body part.

   2.  (REQUIRED) A machine-parsable body part containing an account of
       the reported message handling event.  The purpose of this body
       part is to provide a machine-readable description of the
       condition(s) that caused the report to be generated, along with
       details not present in the first body part that might be useful
       to human experts.  An initial body part, message/delivery-status,
       is defined in [DSN-FORMAT].

   3.  (OPTIONAL) A body part containing the returned message or a
       portion thereof.  This information could be useful to aid human
       experts in diagnosing problems.  (Although it might also be
       useful to allow the sender to identify the message about which
       the report was issued, it is hoped that the envelope-id and
       original-recipient-address returned in the message/report body
       part will replace the traditional use of the returned content for
       this purpose.)

   Return of content can be wasteful of network bandwidth and a variety
   of implementation strategies can be used.  Generally, the sender
   needs to choose the appropriate strategy and inform the recipient of
   the required level of returned content required.  In the absence of
   an explicit request for level of return of content such as that
   provided in [DSN-SMTP], the agent that generated the delivery service
   report SHOULD return the full message content.

   When 8-bit or binary data not encoded in a 7-bit form is to be
   returned, and the return path is not guaranteed to be 8-bit or binary
   capable, two options are available.  The original message MAY be
   re-encoded into a legal 7-bit MIME message or the text/rfc822-headers
   media type MAY be used to return only the original message headers.

4.  The text/rfc822-headers Media Type

   The text/rfc822-headers media type provides a mechanism to label and
   return only the [MAIL] header of a failed message.  The header is not
   the complete message and SHOULD NOT be returned using the message/
   rfc822 media type defined in [MIME-TYPES].  The returned header is
   useful for identifying the failed message and for diagnostics based
   on the Received header fields.

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   The text/rfc822-headers media type is defined as follows:

   Type name:  text

   Subtype name:  rfc822-headers

   Required parameters:  None

   Optional parameters:  None

   Encoding considerations:  7-bit is sufficient for normal mail
      headers, however, if the headers are broken or extended and
      require encoding to make them legal 7-bit content, they MAY be
      encoded with quoted-printable as defined in [MIME].

   Security considerations:  See Section 7 of [RFC6522].

   Interoperability considerations:  none

   Published specification:  [RFC6522]

   Applications that use this media type:  Mail Transfer Agents, Mail
      User Agents, spam detection and reporting modules, virus detection
      modules, and message authentication modules.

   Additional information:

      Magic number(s):  N/A

      File extension(s):  N/A

      Macintosh file type code(s):  N/A

   Person and email address to contact for further information:  Murray
      S. Kucherawy <msk@cloudmark.com>

   Intended usage:  common

   Restrictions on usage:  none

   Author:  Murray S. Kucherawy <msk@cloudmark.com>

   Change controller:  IESG

   The text/rfc822-headers body part SHOULD contain all the mail header
   fields from the message that caused the report.  The header includes
   all header fields prior to the first blank line in the message.  They
   include the MIME-Version and MIME content description fields.

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5.  Registering New Report Types

   Registration of new media types for the purpose of creating a new
   report format SHOULD note in the Intended Usage section of the media
   type registration that the type being registered is suitable for use
   as a report-type (i.e., the second body part) in the context of this
   specification.

6.  IANA Considerations

   IANA has updated the Media Type Registry to indicate that this memo
   contains the current definition of the multipart/report and text/
   rfc822-headers media types, obsoleting [OLD-REPORT].

7.  Security Considerations

   Automated use of report types without authentication presents several
   security issues.  Forging negative reports presents the opportunity
   for denial-of-service attacks when the reports are used for automated
   maintenance of directories or mailing lists.  Forging positive
   reports can cause the sender to incorrectly believe a message was
   delivered when it was not.

   A signature covering the entire multipart/report structure could be
   used to prevent such forgeries; such a signature scheme is, however,
   beyond the scope of this document.

8.  References

8.1.  Normative References

   [KEYWORDS]    Bradner, S., "Key words for use in RFCs to Indicate
                 Requirement Levels", BCP 14, RFC 2119, March 1997.

   [MAIL]        Resnick, P., Ed., "Internet Message Format", RFC 5322,
                 October 2008.

   [MIME]        Freed, N. and N. Borenstein, "Multipurpose Internet
                 Mail Extensions (MIME) Part One: Format of Internet
                 Message Bodies", RFC 2045, November 1996.

   [MIME-REG]    Freed, N. and J. Klensin, "Media Type Specifications
                 and Registration Procedures", BCP 13, RFC 4288,
                 December 2005.

   [MIME-TYPES]  Freed, N. and N. Borenstein, "Multipurpose Internet
                 Mail Extensions (MIME) Part Two: Media Types",
                 RFC 2046, November 1996.

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8.2.  Informative References

   [DSN-FORMAT]  Moore, K. and G. Vaudreuil, "An Extensible Message
                 Format for Delivery Status Notifications", RFC 3464,
                 January 2003.

   [DSN-SMTP]    Moore, K., "Simple Mail Transfer Protocol (SMTP)
                 Service Extension for Delivery Status Notifications
                 (DSNs)", RFC 3461, January 2003.

   [OLD-REPORT]  Vaudreuil, G., "The Multipart/Report Content Type for
                 the Reporting of Mail System Administrative Messages",
                 RFC 3462, January 2003.

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Appendix A.  Acknowledgements

   The author would like to thank Dave Crocker, Frank Ellermann, Ned
   Freed, Randall Gellens, Alexey Melnikov, and Keith Moore for their
   input to this update.

   Thanks also go to Gregory M. Vaudreuil, the original creator of this
   media type.

Author's Address

   Murray S. Kucherawy (editor)
   Cloudmark
   128 King St., 2nd Floor
   San Francisco, CA  94107
   US

   Phone: +1 415 946 3800
   EMail: msk@cloudmark.com

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