An Extensible Format for Email Feedback Reports
RFC 5965

Internet Engineering Task Force (IETF)                   Y. Shafranovich
Request for Comments: 5965                           ShafTek Enterprises
Category: Standards Track                                      J. Levine
ISSN: 2070-1721                                     Taughannock Networks
                                                            M. Kucherawy
                                                               Cloudmark
                                                             August 2010

            An Extensible Format for Email Feedback Reports

Abstract

   This document defines an extensible format and MIME type that may be
   used by mail operators to report feedback about received email to
   other parties.  This format is intended as a machine-readable
   replacement for various existing report formats currently used in
   Internet email.

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/rfc5965.

Copyright Notice

   Copyright (c) 2010 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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Shafranovich, et al.         Standards Track                    [Page 1]
RFC 5965               Format for Feedback Reports           August 2010

Table of Contents

   1. Introduction ....................................................3
      1.1. Purpose ....................................................3
      1.2. Requirements ...............................................4
      1.3. Definitions ................................................4
           1.3.1. General .............................................4
           1.3.2. Email Specific ......................................4
   2. Format of Email Feedback Reports ................................4
   3. The 'message/feedback-report' Content Type ......................5
      3.1. Required Fields ............................................6
      3.2. Optional Fields Appearing Once .............................6
      3.3. Optional Fields Appearing Multiple Times ...................7
      3.4. Notes about URIs ...........................................8
      3.5. Formal Definition ..........................................8
   4. Handling Malformed Reports .....................................10
   5. Transport Considerations .......................................10
   6. Extensibility ..................................................10
   7. IANA Considerations ............................................11
      7.1. MIME Type Registration of 'message/feedback-report' .......11
      7.2. Feedback Report Header Fields .............................12
      7.3. Feedback Report Type Values ...............................15
   8. Security Considerations ........................................17
      8.1. Inherited from RFC 3462 ...................................17
      8.2. Interpretation ............................................17
      8.3. Attacks against Authentication Methods ....................17
      8.4. Intentionally Malformed Reports ...........................18
      8.5. Omitting Data from ARF Reports ............................18
      8.6. Automatically Generated ARF Reports .......................18
      8.7. Attached Malware ..........................................18
      8.8. The User-Agent Field ......................................18
      8.9. Malformed Messages ........................................19
   9. References .....................................................19
      9.1. Normative References ......................................19
      9.2. Informative References ....................................20
   Appendix A.  Acknowledgements .....................................22
   Appendix B.  Sample Feedback Reports ..............................22