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Email Feedback Report Type Value: not-spam
RFC 6430

Document Type RFC - Proposed Standard (November 2011)
Authors Barry Leiba , Kepeng Li
Last updated 2015-10-14
Replaces draft-li-marf-not-spam-feedback
RFC stream Internet Engineering Task Force (IETF)
Additional resources Mailing list discussion
Stream WG state Submitted to IESG for Publication
Document shepherd Murray Kucherawy
Shepherd write-up Show Last changed 2011-08-02
IESG IESG state RFC 6430 (Proposed Standard)
Action Holders
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD Pete Resnick
Send notices to (None)
RFC 6430
Internet Engineering Task Force (IETF)                             K. Li
Request for Comments: 6430                                      B. Leiba
Category: Standards Track                            Huawei Technologies
ISSN: 2070-1721                                            November 2011

               Email Feedback Report Type Value: not-spam


   This document defines a new Abuse Reporting Format (ARF) feedback
   report type value: "not-spam".  It can be used to report an email
   message that was mistakenly marked as spam.

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

Copyright Notice

   Copyright (c) 2011 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
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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RFC 6430              Email Feedback Type: not-spam        November 2011

Table of Contents

   1. Introduction ....................................................2
      1.1. Discussion .................................................2
   2. Feedback Report Type: not-spam ..................................3
   3. Example .........................................................3
   4. Security Considerations .........................................5
   5. IANA Considerations .............................................6
   6. Acknowledgements ................................................6
   7. References ......................................................6
      7.1. Normative References .......................................6
      7.2. Informative References .....................................6

1.  Introduction

   In RFC 5965 [RFC5965], an Abuse Reporting Format (ARF) is defined for
   reporting email abuse.  Currently, two feedback report types are
   defined that are related to the spam problem and that can be used to
   report abusive or fraudulent email messages:

   o  abuse: indicates unsolicited email or some other kind of email

   o  fraud: indicates some kind of fraud or phishing activity.

   This specification defines a new feedback report type: "not-spam".
   It can be used to report a message that was mistakenly marked as

1.1.  Discussion

   In some cases, the email client receives an email message that was
   incorrectly tagged as spam, perhaps by the email system, or
   accidentally by the user.  The email client accepts the end user's
   "not-spam" report instruction, retrieves information related to the
   message, and reports this email as not-spam to the email operator.
   When the email operator receives the report, it can determine what
   action is appropriate for the particular message and user.  (The
   requirement for a not-spam report type is from the Open Mobile
   Alliance (OMA) Spam Report Requirement Document [OMA-SpamRep-RD].)

   For example, in response to a "not-spam" report, the email system can
   remove the spam tag or otherwise reclassify the message, possibly
   preventing similar email for this user from being marked as spam in
   the future.  The report can be used to adjust the training of an
   automated classifier.  After processing the report, the email

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RFC 6430              Email Feedback Type: not-spam        November 2011

   operator might send a notification to the email client about the
   processing result (for example, by moving the message from one
   mailbox to another, such as from "Junk" to "Inbox").

   In most cases, "not-spam" reports will probably not be taken on their
   own, but will be considered along with other information, analysis of
   the message, etc.  Because different users have different needs and
   different views of what constitutes spam, reports from one user might
   or might not be applicable to others.  And because users might
   sometimes press a "report not spam" button accidentally, immediate
   strong action, such as marking all similar messages as "good" based
   on a single report, is probably not the right approach.  Recipients
   of "not-spam" reports need to consider what's right in their

   There are anti-spam systems that use (non-standard) "not spam"
   feedback today.  All of them take the reports and mix them with other
   spam reports and other data, using their own algorithms, to determine
   appropriate action.  In no case do the existing systems use a "not
   spam" report as an immediate, automatic override.

   The feedback types "abuse" and "not-spam" can be taken as opposites.
   A mistaken "not-spam" report could be countermanded by a subsequent
   "abuse" report from the same user, and an operator could consider
   collected reports of "abuse" and "not-spam" in making future

2.  Feedback Report Type: not-spam

   This document defines a new feedback report type, "not-spam", which
   extends the Email Feedback Reports specification [RFC5965].

   In the first MIME part of the feedback report message, the end user
   or the email client can add information to indicate why the message
   is not considered as spam -- for example, because the originator or
   its domain is well known.

3.  Example

   In the example, Joe, a pharmaceuticals sales representative, has
   received a message about discount pharmaceuticals.  Because that is a
   frequent subject of spam email, the message has been marked as spam
   -- incorrectly, in this case.  Joe has reported it as "not-spam", and
   this is an example of the report, shortened (the "[...etc...]" part)
   for presentation here.

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RFC 6430              Email Feedback Type: not-spam        November 2011

   Note that the message has been signed using DomainKeys Identified
   Mail (DKIM) [RFC6376] -- a good security practice as suggested in
   Section 8.2 of RFC 5965 [RFC5965].

      DKIM-Signature: v=1; a=rsa-sha256; s=abuse;;
        c=simple/simple; q=dns/txt;;
      From: <>
      Date: Thu, 8 Mar 2005 17:40:36 EDT
      Subject: FW: Discount on pharmaceuticals
      To: <>
      Message-ID: <>
      MIME-Version: 1.0

      Content-Type: multipart/report; report-type=feedback-report;

      Content-Type: text/plain; charset="US-ASCII"
      Content-Transfer-Encoding: 7bit

      This is an email abuse report for an email message received
      from IP on Thu, 8 Mar 2005 14:00:00 EDT.
      For more information about this format please see
      Comment: I sell pharmaceuticals, so this is not spam for me.

      Content-Type: message/feedback-report

      Feedback-Type: not-spam
      User-Agent: SomeGenerator/1.0
      Version: 1

      Content-Type: message/rfc822
      Content-Disposition: inline

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RFC 6430              Email Feedback Type: not-spam        November 2011

      Received: from
           ( [])
           by with ESMTP id M63d4137594e46;
           Thu, 08 Mar 2005 14:00:00 -0400
      From: <>
      To: <Undisclosed Recipients>
      Subject: Discount on pharmaceuticals
      MIME-Version: 1.0
      Content-type: text/plain
      Date: Thu, 02 Sep 2004 12:31:03 -0500

      Hi, Joe.  I got a lead on a source for discounts on
      pharmaceuticals, and I thought you might be interested.

                        Example 1: not-spam Report

4.  Security Considerations

   All of the security considerations from the Email Feedback Reports
   specification [RFC5965] are inherited here.  In addition, the Email
   Feedback Reports Applicability Statement [MARF-AS] contains important
   information about trust relationships and other security- and
   integrity-related aspects of accepting abuse feedback.

   In particular, not-spam reports will likely be used in an attack on a
   filtering system, reporting true spam as "not-spam".  Even in absence
   of malice, some not-spam reports might be made in error, or will only
   apply to the user sending the report.  Operators need to be careful
   in trusting such reports, beyond their applicability to the specific
   user in question.

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RFC 6430              Email Feedback Type: not-spam        November 2011

5.  IANA Considerations

   IANA has registered the newly defined feedback type name: "not-spam",
   according to the instructions in Section 7.3 of the base
   specification [RFC5965].

   The following has been added to the "Feedback Report Type Values"

   Feedback Type Name:  not-spam

   Description:  Indicates that the entity providing the report does not
      consider the message to be spam.  This may be used to correct a
      message that was incorrectly tagged or categorized as spam.

   Published in:  this document

   Status:  current

6.  Acknowledgements

   The authors would like to thank Murray S. Kucherawy and Bert
   Greevenbosch for their discussion and review, and J.D. Falk for
   suggesting some explanatory text.

7.  References

7.1.  Normative References

   [RFC5965]  Shafranovich, Y., Levine, J., and M. Kucherawy, "An
              Extensible Format for Email Feedback Reports", RFC 5965,
              August 2010.

7.2.  Informative References

   [MARF-AS]  Falk, J., "Creation and Use of Email Feedback Reports: An
              Applicability Statement for the Abuse Reporting Format
              (ARF)", Work in Progress, September 2011.

              Open Mobile Alliance, "Mobile Spam Reporting
              Requirements", Candidate Version 1.0 OMA-RD-SpamRep-V1_0-
              20101123-C, November 2010, <http://

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RFC 6430              Email Feedback Type: not-spam        November 2011

   [RFC6376]  Crocker, D., Ed., Hansen, T., Ed., and M. Kucherawy, Ed.,
              "DomainKeys Identified Mail (DKIM) Signatures", RFC 6376,
              September 2011.

Authors' Addresses

   Kepeng Li
   Huawei Technologies
   Huawei Base, Bantian, Longgang District
   Shenzhen, Guangdong  518129
   P.R. China

   Phone: +86-755-28974289

   Barry Leiba
   Huawei Technologies

   Phone: +1 646 827 0648

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