Domain-based Message Authentication, Reporting, and Conformance (DMARC) Failure Reporting
draft-ietf-dmarc-failure-reporting-24

DMARC                                                      S. Jones (ed)
Internet-Draft                                                 DMARC.org
Obsoletes: 7489 (if approved)                             A. Vesely (ed)
Updates: 6591 (if approved)                                         Tana
Intended status: Standards Track                          9 January 2026
Expires: 13 July 2026

Domain-based Message Authentication, Reporting, and Conformance (DMARC)
                           Failure Reporting
                 draft-ietf-dmarc-failure-reporting-24

Abstract

   Domain-based Message Authentication, Reporting, and Conformance
   (DMARC) is a mechanism by which a Domain Owner can request feedback
   about email messages using their domain in the From: address field.
   This document describes "failure reports", or "failed message
   reports", which provide details about individual messages that failed
   to authenticate according to the DMARC mechanism.

   This document updates RFC 6591 and obsoletes RFC 7489.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 13 July 2026.

Copyright Notice

   Copyright (c) 2026 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 (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.

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   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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Document Status . . . . . . . . . . . . . . . . . . . . .   4
   2.  DMARC Failure Reports . . . . . . . . . . . . . . . . . . . .   4
   3.  Other Failure Reports . . . . . . . . . . . . . . . . . . . .   5
   4.  Reporting Format Update . . . . . . . . . . . . . . . . . . .   5
   5.  Verifying External Destinations . . . . . . . . . . . . . . .   6
     5.1.  Transport . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  Feedback Report Header Fields Registry Update . . . . . .   7
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   7
     7.1.  Data Exposure Considerations  . . . . . . . . . . . . . .   8
     7.2.  Report Recipients . . . . . . . . . . . . . . . . . . . .   8
     7.3.  Additional Damage . . . . . . . . . . . . . . . . . . . .   9
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
     8.1.  Denial of Service . . . . . . . . . . . . . . . . . . . .  10
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .  10
   10. Informative References  . . . . . . . . . . . . . . . . . . .  11
   Appendix A.  Example Failure Report . . . . . . . . . . . . . . .  11
   Appendix B.  Change Log {change-log}  . . . . . . . . . . . . . .  15
     B.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  15
     B.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  16
     B.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  16
     B.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  16
     B.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  16
     B.6.  05 to 06  . . . . . . . . . . . . . . . . . . . . . . . .  16
     B.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.8.  07 to 08  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.9.  08 to 09  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.10. 09 to 10  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.11. 10 to 11  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.12. 11 to 12  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.13. 12 to 13  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.14. 13 to 14  . . . . . . . . . . . . . . . . . . . . . . . .  17
     B.15. 14 to 15  . . . . . . . . . . . . . . . . . . . . . . . .  18
     B.16. 15 to 16  . . . . . . . . . . . . . . . . . . . . . . . .  18
     B.17. 16 to 17  . . . . . . . . . . . . . . . . . . . . . . . .  18
     B.18. 17 to 18  . . . . . . . . . . . . . . . . . . . . . . . .  18
     B.19. 18 to 19  . . . . . . . . . . . . . . . . . . . . . . . .  18
     B.20. 19 to 20  . . . . . . . . . . . . . . . . . . . . . . . .  18

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     B.21. 20 to 21  . . . . . . . . . . . . . . . . . . . . . . . .  18
     B.22. 21 to 22  . . . . . . . . . . . . . . . . . . . . . . . .  19
     B.23. 22 to 23  . . . . . . . . . . . . . . . . . . . . . . . .  19
     B.24. 23 to 24  . . . . . . . . . . . . . . . . . . . . . . . .  19
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  19

1.  Introduction

   RFC EDITOR: PLEASE REMOVE THE FOLLOWING PARAGRAPH BEFORE PUBLISHING:
   The source for this draft is maintained in GitHub at:
   https://github.com/ietf-wg-dmarc/draft-ietf-dmarc-failure-reporting
   (https://github.com/ietf-wg-dmarc/draft-ietf-dmarc-failure-reporting)

   Domain-based Message Authentication, Reporting, and Conformance
   (DMARC) [I-D.ietf-dmarc-dmarcbis] is a mechanism by which a mail-
   originating organization can express domain-level policies and
   preferences for message validation, disposition, and reporting, that
   can be used by a mail-receiving organization to improve mail
   handling.  This document focuses on one type of reporting that can be
   requested under DMARC.

   Failure reports provide detailed information about the failure of a
   single message, or a group of similar messages failing for the same
   reason.  Their purpose is twofold.  On the one hand they are meant to
   aid in cases where a Domain Owner wishes to determine the cause of
   failures that were part of aggregate reports (see
   [I-D.ietf-dmarc-aggregate-reporting]).  On the other hand, they can
   allow the Domain Owner to quickly identify and address harmful
   messages involving direct domain abuse.  It is important to note that
   these reports can contain the header fields or sometimes the entire
   content of a failed message, which may contain personally
   identifiable information (PII).  The potential disclosure of PII
   should be considered when deciding whether to request failure reports
   as a Domain Owner, or what information to include or redact in
   failure reports when creating them as a Mail Receiver, or whether to
   create failure reports at all.  Refer to Section 7 for more
   discussion on privacy considerations.

1.1.  Terminology

   There are a number of terms defined in Section 3.2 of
   [I-D.ietf-dmarc-dmarcbis] that are used within this document.
   Understanding those definitions will aid in reading this document.

   The format of DMARC failure reports is derived from Authentication
   Failure Reporting Using the Abuse Reporting Format ([RFC6591]) and
   the terms defined there are used here.

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   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

1.2.  Document Status

   This document, in part, along with DMARCbis [I-D.ietf-dmarc-dmarcbis]
   DMARCbis Aggregate Reporting [I-D.ietf-dmarc-aggregate-reporting],
   obsoletes and replaces [RFC7489].

2.  DMARC Failure Reports

   Besides the header fields or the entire contents of a failed message,
   failure reports supply details about transmission and DMARC
   authentication, which may aid a Domain Owner in determining the cause
   of an authentication failure.

   Failure reports are normally generated and sent almost immediately
   after the Mail Receiver detects a DMARC failure.  Rather than waiting
   for an aggregate report, these reports are useful for quickly
   notifying the Domain Owners when there is an authentication failure.
   Failure reports also provide more information about the failed
   message than is available in an aggregate report.  This allows the
   failure report consumer to better determine whether the failure is of
   a message that the domain owner intended to authenticate or one for
   which use of its domain was not authorized.

   These reports should include as much of the message header fields and
   body as possible, consistent with the reporting party's privacy
   policies, to enable the Domain Owner to diagnose the authentication
   failure.

   When a Domain Owner requests failure reports for the purpose of
   forensic analysis, and the Mail Receiver is willing to provide such
   reports, the Mail Receiver generates and sends a message using the
   format described in [RFC6591]; this document updates that reporting
   format, as described in Section 4.

   The destination(s) to which failure reports are sent, and options for
   when they will be sent, are defined by the "ruf" and "fo" tags as
   provided in Section 4.7 of [I-D.ietf-dmarc-dmarcbis].

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   When multiple URIs are provided to receive failure reports, the
   report generator MUST make an attempt to deliver to each of them.
   External destinations MUST be verified, see Section 5.  Report
   generators MUST NOT consider "ruf" tags in DMARC Policy Records
   having a "psd=y" tag, unless there are specific agreements between
   the interested parties.

   Report generators MUST implement a rate-limit on outgoing reports so
   as not to flood report consumers with excessive reports, which would
   allow denial-of-service; see Section 8.1.

3.  Other Failure Reports

   This document describes only DMARC failure reports.  DKIM failure
   reports and SPF failure reports are described in [RFC6591].  A Mail
   Receiver generating DMARC failure reports MAY issue failure reports
   specific to the failed authentication mechanism instead of, or in
   addition to, DMARC failure reports, based on its own policy, the
   failure in question, and the content of the "fo" tag in the retrieved
   DMARC Policy Record.

   Note that DKIM failure reports and SPF failure reports can also be
   requested using the methods described in [RFC6651] and [RFC6652],
   respectively.  Report Generators are free to follow any of the
   specifications.

4.  Reporting Format Update

   Operators implementing this specification also implement an augmented
   version of [RFC6591] as follows:

   1.  A DMARC failure report includes the following ARF header fields,
       with the indicated normative requirement levels:

       *  Identity-Alignment (REQUIRED; defined below)

       *  Delivery-Result (OPTIONAL)

       *  DKIM-Domain, DKIM-Identity, DKIM-Selector (REQUIRED for DKIM
          failures of an aligned identifier)

       *  DKIM-Canonicalized-Header, DKIM-Canonicalized-Body (OPTIONAL
          if reporting a DKIM failure)

       *  SPF-DNS (REQUIRED for SPF failure of an aligned identifier)

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   2.  The "Identity-Alignment" field is defined to contain a comma-
       separated list of authentication mechanism names that failed to
       authenticate an aligned identity, or the keyword "none" if none
       did.  ABNF ([RFC5234], importing CFWS from [RFC5322]):

   id-align     = "Identity-Alignment:" [CFWS]
                    ( "none" /
                      dmarc-method *( [CFWS] "," [CFWS] dmarc-method ) )
                    [CFWS]

   dmarc-method = ( "dkim" / "spf" )
                    ; each may appear at most once in an id-align

   3.  Authentication Failure Type "dmarc" is defined for the Auth-
       Failure field, which is to be used when a failure report is
       generated because some or all of the authentication mechanisms
       failed to produce aligned identifiers.  Note that a failure
       report generator MAY also independently produce an ARF message
       for any or all of the underlying authentication methods.

5.  Verifying External Destinations

   It is possible to specify destinations for failure reports that are
   outside of the Organizational Domain of the DMARC Policy Record that
   was requesting the reports.  These destinations are commonly referred
   to as "external destinations" and may represent a different domain
   controlled by the same organization, a contracted report processing
   service, or some other arrangement.

   In case of external destinations, a Mail Receiver who generates
   failure reports MUST use the Verifying External Destinations
   procedure described in Section 4 of
   [I-D.ietf-dmarc-aggregate-reporting], substituting the "ruf" tag
   where the "rua" tag appears in that procedure.

   This prevents a bad actor from publishing a DMARC Policy Record
   requesting failure reports to an external destination, and then
   deliberately sending messages that will generate failure reports as a
   form of abuse.  It also prevents a Domain Owner from unilaterally
   publishing a DMARC Policy Record with an external destination for
   failure reports, forcing the external destination to deal with
   unwanted messages and potential privacy issues.

5.1.  Transport

   Email streams carrying DMARC failure reports SHOULD be DMARC-aligned.

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   We recommend that reporters set a reasonable rate-limit for the
   number of failure reports sent to any recipient to avoid overloading
   recipient systems.  Unaligned reports may in turn produce subsequent
   failure reports that could cause mail loops.

6.  IANA Considerations

6.1.  Feedback Report Header Fields Registry Update

   IANA is requested to change the "Identity-Alignment" entry in the
   "Feedback Report Header Fields" registry, which is part of the
   "Messaging Abuse Reporting Format (MARF) Parameters" registry group,
   to refer to this document.

7.  Privacy Considerations

   The generation and transmission of DMARC failure reports raise
   significant privacy concerns that must be carefully considered before
   deployment.

   Given these factors, many large-scale providers limit or entirely
   disable the generation of failure reports, preferring to rely on
   aggregate reports, which provide statistical visibility without
   exposing sensitive content.  Operators that choose to enable failure
   reporting are strongly encouraged to:

   *  Limit the scope and duration of use to targeted diagnostic
      activities.
   *  Ensure that reporting URIs are carefully controlled and validated.
   *  Apply minimization techniques, such as redaction of message bodies
      and header fields, to reduce sensitive data exposure.
   *  Always transmit reports over secure channels.

   In summary, while DMARC failure reports can offer diagnostic value,
   the associated privacy concerns have led many operators to restrict
   their use.  Aggregate reports remain the recommended mechanism for
   gaining visibility into authentication results while preserving the
   confidentiality of end-user communications.

   Particular privacy-specific issues are explored below.

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7.1.  Data Exposure Considerations

   Failure reports may include PII and non-public information (NPI) from
   messages that fail to authenticate, since these reports may contain
   message content as well as trace header fields.  These reports may
   expose sender and recipient identifiers (e.g., RFC5322.From
   addresses), and although the [RFC5965] format used for failed-message
   reporting supports redaction ([RFC6590]), failed-message reporting is
   capable of exposing the entire message to the Report Consumer.  They
   may also expose PII, sensitive business data, or other confidential
   communications to unintended recipients.  Such exposure can create
   regulatory, legal, and operational risks for both senders and
   receivers.  Examples include product launches, termination notices
   for employees, or calendar data.  Even innocuous-seeming failures
   (such as malformed or "broken" calendar invitations) can result in
   the leakage of private communications.

   Domain Owners requesting reports will receive information about mail
   using their domain, but which they did not actually cause to be sent.
   This might provide valuable insight into content used in abusive
   messages, but it might also expose PII or NPI from legitimate
   messages mistakenly or accidentally failing authentication.

   Information about the final destination of mail, where it might
   otherwise be obscured by intermediate systems, may be exposed through
   a failure report.  A commonly cited example is exposure of members of
   mailing lists when one list member sends messages to the list, and
   failure reports are generated when that message is delivered to other
   list members.  Those failure reports would be sent to the Domain
   Owner of the list member posting the message, or their delegated
   Report Consumer(s).

   Similarly, when message forwarding arrangements exist, Domain Owners
   requesting reports may receive information about mail forwarded to
   domains that were not originally part of their messages' recipient
   list.  This means that destinations previously unknown to the Domain
   Owner may now become visible.

7.2.  Report Recipients

   A DMARC Policy Record can specify that reports should be sent to a
   Report Consumer operating on behalf of the Domain Owner.  This might
   be done when the Domain Owner sends reports to an entity to monitor
   mail streams for deliverability, performance issues, or abuse.
   Receipt of such data by third parties may or may not be permitted by
   the Mail Receiver's privacy policy, terms of use, et cetera.  Domain
   Owners and Mail Receivers should both review and understand whether
   their own internal policies constrain the use and transmission of

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   DMARC reporting.

   Some potential exists for Report Consumers to perform traffic
   analysis, making it possible to obtain metadata about the Mail
   Receiver's traffic.  In addition to verifying compliance with
   policies, Mail Receivers need to consider that before sending reports
   to a third party.  On the other hand, a Domain Owner may publish a
   destination address that appears to be an Internal Report Consumer
   but is actually a forwarding address; in this case, the final
   destination of a report is not guaranteed.

7.3.  Additional Damage

   The risks associated with failure reports are compounded by volume
   and content distribution concerns.  Partially or unredacted reports
   may propagate large amounts of spam, phishing, or malware content,
   all of which may require special handling by Report Consumers or
   other recipients to avoid incidents.  This underscores the need to
   avoid misconfiguration of the destinations in the "ruf" reporting
   URIs, and the suggestions for redaction in this document, for example
   using the method described in [RFC6590].  All of these concerns are
   heightened for high-volume domains.  To mitigate such concerns, the
   following steps should be considered:

   By report generators:

   *  Help prevent accidental access to potentially-malicious URIs by
      substituting hxxp for http;
   *  remove attachments which could embed malicious payload.

   By report consumers:

   *  isolate report streams from other mail streams;
   *  use sandboxes in evaluating failure reports;
   *  use network segmentation;
   *  limit access to failure reports to authorized individuals with
      appropriate security training.

8.  Security Considerations

   While reviewing this document and its Security Considerations, the
   reader should also review the Privacy Considerations above, as well
   as the Privacy Considerations and Security Considerations in sections
   10 and 11 of [I-D.ietf-dmarc-dmarcbis]; and in sections 7 and 8 of
   [I-D.ietf-dmarc-aggregate-reporting].

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8.1.  Denial of Service

   Failure reports represent a possible denial-of-service attack that
   could be perpetrated by an attacker who sends numerous messages
   purporting to be from the intended victim Domain Owner but which fail
   both SPF and DKIM; this would cause participating Mail Receivers to
   send failure reports to the Domain Owner or its delegate(s),
   potentially in large numbers.  Accordingly, participating Mail
   Receivers are encouraged to aggregate these reports as much as is
   practical, using the Incidents field of the Abuse Reporting Format
   [RFC5965].  Indeed, the aim is not to count each and every failure,
   but rather to report different failure conditions.  Various pruning
   techniques are possible, including the following:

   *  store reports for a period of time before sending them, allowing
      detection, collection, and consolidation of like incidents;

   *  apply rate limiting, such as a maximum number of reports per
      minute that will be generated (and the remainder discarded.)

9.  Normative References

   [I-D.ietf-dmarc-aggregate-reporting]
              Brotman, A., "Domain-based Message Authentication,
              Reporting, and Conformance (DMARC) Aggregate Reporting",
              Work in Progress, Internet-Draft, draft-ietf-dmarc-
              aggregate-reporting-32, 17 March 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-dmarc-
              aggregate-reporting-32>.

   [I-D.ietf-dmarc-dmarcbis]
              Herr, T. and J. R. Levine, "Domain-based Message
              Authentication, Reporting, and Conformance (DMARC)", Work
              in Progress, Internet-Draft, draft-ietf-dmarc-dmarcbis-41,
              4 April 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-dmarc-dmarcbis-41>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <https://www.rfc-editor.org/info/rfc5234>.

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   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              DOI 10.17487/RFC5322, October 2008,
              <https://www.rfc-editor.org/info/rfc5322>.

   [RFC5965]  Shafranovich, Y., Levine, J., and M. Kucherawy, "An
              Extensible Format for Email Feedback Reports", RFC 5965,
              DOI 10.17487/RFC5965, August 2010,
              <https://www.rfc-editor.org/info/rfc5965>.

   [RFC6590]  Falk, J., Ed. and M. Kucherawy, Ed., "Redaction of
              Potentially Sensitive Data from Mail Abuse Reports",
              RFC 6590, DOI 10.17487/RFC6590, April 2012,
              <https://www.rfc-editor.org/info/rfc6590>.

   [RFC6591]  Fontana, H., "Authentication Failure Reporting Using the
              Abuse Reporting Format", RFC 6591, DOI 10.17487/RFC6591,
              April 2012, <https://www.rfc-editor.org/info/rfc6591>.

   [RFC6692]  Clayton, R. and M. Kucherawy, "Source Ports in Abuse
              Reporting Format (ARF) Reports", RFC 6692,
              DOI 10.17487/RFC6692, July 2012,
              <https://www.rfc-editor.org/info/rfc6692>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

10.  Informative References

   [RFC6651]  Kucherawy, M., "Extensions to DomainKeys Identified Mail
              (DKIM) for Failure Reporting", RFC 6651,
              DOI 10.17487/RFC6651, June 2012,
              <https://www.rfc-editor.org/info/rfc6651>.

   [RFC6652]  Kitterman, S., "Sender Policy Framework (SPF)
              Authentication Failure Reporting Using the Abuse Reporting
              Format", RFC 6652, DOI 10.17487/RFC6652, June 2012,
              <https://www.rfc-editor.org/info/rfc6652>.

   [RFC7489]  Kucherawy, M., Ed. and E. Zwicky, Ed., "Domain-based
              Message Authentication, Reporting, and Conformance
              (DMARC)", RFC 7489, DOI 10.17487/RFC7489, March 2015,
              <https://www.rfc-editor.org/info/rfc7489>.

Appendix A.  Example Failure Report

   This is the full content of a sample failure message, including the
   message header.

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   Received: from gen.example (gen.example [192.0.2.1])
     (TLS: TLS1.3,256bits,ECDHE_RSA_AES_256_GCM_SHA384)
     by mail.consumer.example with ESMTPS
     id 00000000005DC0DD.0000442E; Tue, 19 Jul 2022 07:57:50 +0200
   DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple;
     d=gen.example; s=mail; t=1658210268;
     bh=rCrh1aFDE8d/Fltt8wbcu48bLOu4OM23QXqphUZPAIM=;
     h=From:To:Date:Subject:From;
     b=IND9JkuwF9/5841kzxMbPeej0VYimVzNKozR2R89M8eYO2zOlCBblx507Gz0YK7mE
      /h6pslWm0ODBVFzLlwY9CXv4Vu62QsN0RBIXHPjEXOkoM2VCD5zCd+5i5dtCFX7Mxh
      LThb2ZJ3efklbSB9RQRwxcmRvCPV7z6lt/Ds9sucVE1RDODYHjx+iWnAUQrlos6ZQb
      u/YOUGjf60LPpyljfPu3EpFwo80mSHyQlP/4S5KEykgPQMgCqLPPKvJwu1aAIDj+jG
      q2ylO3fmc/ERDeDWACtR67YNabEKBWtjqCRLNxKttazViJTZ5drcLfpX0853KoougX
      Rltp7zdoLdy4A==
   From: DMARC Filter <DMARC@gen.example>;
   To: dmarcfail@consumer.example
   Date: Tue, 19 Jul 2022 00:57:48 -0500 (CDT)
   Subject: FW: This is the original subject
   Mime-Version: 1.0
   Content-Type: multipart/report; report-type=feedback-report;
     boundary="=_mime_boundary_"
   Message-Id: <20220719055748.4AE9D403CC@gen.example>;

   This is a MIME-formatted message.  If you see this text it means that
   your E-mail software does not support MIME-formatted messages.

   --=_mime_boundary_
   Content-Type: text/plain; charset=utf-8
   Content-Disposition: inline
   Content-Transfer-Encoding: 7bit

   This is an authentication failure report for an email message
   received from IP 192.0.2.2 on Tue, 19 Jul 2022 00:57:48 -0500.

   --=_mime_boundary_
   Content-Type: message/feedback-report
   Content-Transfer-Encoding: 7bit

   Feedback-Type: auth-failure
   Version: 1
   User-Agent: DMARC-Filter/1.2.3
   Auth-Failure: dmarc
   Authentication-Results: gen.example;
     dmarc=fail header.from=consumer.example
   Identity-Alignment: dkim
   DKIM-Domain: consumer.example
   DKIM-Identity: @consumer.example
   DKIM-Selector: epsilon

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   Original-Envelope-Id: 65E1A3F0A0
   Original-Mail-From: author=gen.example@forwarder.example
   Source-IP: 192.0.2.2
   Source-Port: 12345
   Reported-Domain: consumer.example

   --=_mime_boundary_
   Content-Type: message/rfc822; charset=utf-8
   Content-Transfer-Encoding: 7bit

   Authentication-Results: gen.example;
     dkim=permerror header.d=forwarder.example header.b="EjCbN/c3";
     dkim=temperror header.d=forwarder.example header.b="mQ8GEWPc";
     dkim=permerror header.d=consumer.example header.b="hETrymCb";
     dkim=neutral header.d=consumer.example header.b="C2nsAp3A";
   Received: from mail.forwarder.example
     (mail.forwarder.example [IPv6:2001:db8::23ac])
     by mail.gen.example (Postfix) with ESMTP id 5E8B0C159826
     for <x@gen.example>; Sun, 14 Aug 2022 07:58:29 -0700 (PDT)
   Received: from mail.forwarder.example (localhost [127.0.0.1])
     by mail.forwarder.example (Postfix) with ESMTP id 4Ln7Qw4fnvz6Bq
     for <x@gen.example>; Tue, 19 Jul 2022 07:57:44 +0200
   DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed;
     d=forwarder.example; s=ed25519-59hs; t=1658210264;
     x=1663210264; bh=KYH/g7ForvDbnyyDLYSjauMYMW6sEIqu75/9w3OIONg=;
     h=Message-ID:Date:List-Id:List-Archive:List-Post:List-Help:
      List-Subscribe:List-Unsubscribe:List-Owner:MIME-Version:Subject:
      To:References:From:In-Reply-To:Content-Type:
      Content-Transfer-Encoding:autocrypt:cc:content-transfer-encoding:
      content-type:date:from:in-reply-to:message-id:mime-version:
      openpgp:references:subject:to;
     b=EjCbN/c3bTU4QkZH/zwTbYxBDp0k8kpmWSXh5h1M7T8J4vtRo+hvafJazT3ZRgq+7
      +4dzEQwUhl+NOJYXXNUAA==
   DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
     d=forwarder.example; s=rsa-wgJg; t=1658210264; x=1663210264;
     bh=KYH/g7ForvDbnyyDLYSjauMYMW6sEIqu75/9w3OIONg=;
     h=Message-ID:Date:List-Id:List-Archive:List-Post:List-Help:
      List-Subscribe:List-Unsubscribe:List-Owner:MIME-Version:Subject:
      To:References:From:In-Reply-To:Content-Type:
      Content-Transfer-Encoding:autocrypt:cc:content-transfer-encoding:
      content-type:date:from:in-reply-to:message-id:mime-version:
      openpgp:references:subject:to;
     b=mQ8GEWPcVpBpeqQ88pcbXpGHBT0J/Rwi8Zd2WZTXWWneQGRCOJLRcbBJpjqnrwtqd
      76IqawH86tihz4Z/12J1GBCdNx1gfazsoI3yaqfooRDYg0mSyZHrYhQBmodnPcqZj4
      /25L5278sc/UNrYO9az2n7R/skbVZ0bvSo2eEiGU8fcpO8+a5SKNYskhaviAI4eGIB
      iRMdEP7gP8dESdnZguNbY5HI32UMDpPPNqajzd/BgcqbveYpRrWCDOhcY47POV7GHM
      i/KLHiZXtJsL3/Pr/4TL+HTjdX8EDSsy1K5/JCvJCFsJHnSvkEaJQGLn/2m03eW9r8
      9w1bQ90aY+VCQ==

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   X-Original-To: users@forwarder.example
   Received: from mail.consumer.example
     (mail.consumer.example [192.0.2.4])
     (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
      key-exchange ECDHE (P-256) server-signature ECDSA (P-384)
      server-digest SHA384)
     (Client did not present a certificate)
     by mail.forwarder.example (Postfix) with ESMTPS id 4Ln7Qs55xmz4nP
     for <users@forwarder.example>;
     Tue, 19 Jul 2022 07:57:41 +0200 (CEST)
   Authentication-Results: mail.forwarder.example;
     arc=none smtp.remote-ip=192.0.2.4
   Authentication-Results: mail.forwarder.example;
     dkim=pass (512-bit key; secure) header.d=consumer.example
      header.i=@consumer.example header.a=ed25519-sha256
      header.s=epsilon header.b=hETrymCb;
     dkim=pass (1152-bit key; secure) header.d=consumer.example
      header.i=@consumer.example header.a=rsa-sha256
      header.s=delta header.b=C2nsAp3A
   DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed;
     d=consumer.example; s=epsilon; t=1658210255;
     bh=KYH/g7ForvDbnyyDLYSjauMYMW6sEIqu75/9w3OIONg=;
     h=Date:Subject:To:References:From:In-Reply-To;
     b=hETrymCbz6T1Dyo5dCG9dk8rPykKLdhJCPFeJ9TiiP/kaoN2afpUYtj+SrI+I83lp
      p1F/FfYSGy7zz3Q3OdxBA==
   DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
     d=consumer.example; s=delta; t=1658210255;
     bh=KYH/g7ForvDbnyyDLYSjauMYMW6sEIqu75/9w3OIONg=;
     h=Date:To:References:From:In-Reply-To;
     b=C2nsAp3AMNX33Nq7nN/StPo921xE3XGF8Ju3iAKdYB3EKhsril0N5IjWGlglJECst
      jLNKSo7KWZZ2lkH/dVZ9Rs1GHT2uaKy1sc/xmNIC5rHdhrxammiwpTSo4PsT8disfc
      3DVF6Q62n0EsdLFqcw1KY8A9inFqYKY2tqoo+y4zMtItqCYx3xjsj3I0IFLuX
   Author: Message Author <author@consumer.example>
   Received: from [192.0.2.8] (host-8-2-0-192.isp.example [192.0.2.8])
     (AUTH: CRAM-MD5 uXDGrn@SYT0/k, TLS: TLS1.3,128bits,
     ECDHE_RSA_AES_128_GCM_SHA256)
     by mail.consumer.example with ESMTPSA
     id 00000000005DC076.00004417; Tue, 19 Jul 2022 07:57:35 +0200
   Message-ID: <2431dc66-b010-c9cc-4f2b-a1f889f8bdb4@consumer.example>
   Date: Tue, 19 Jul 2022 07:57:33 +0200
   List-Id: <users.forwarder.example>
   List-Post: <mailto:users@forwarder.example>
   List-Help: <mailto:users+help@forwarder.example>
   List-Subscribe: <mailto:users+subscribe@forwarder.example>
   List-Unsubscribe: <mailto:users+unsubscribe@forwarder.example>
   List-Owner: <mailto:users+owner@forwarder.example>
   Precedence: list
   MIME-Version: 1.0

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   Subject: This is the original subject
   Content-Language: en-US
   To: users@forwarder.example
   Authentication-Results: consumer.example; auth=pass (details omitted)
   From: Message Author <author@consumer.example>
   In-Reply-To: <20220718102753.0f6d9dde.cel@example.com>
   Content-Type: text/plain; charset=UTF-8; format=flowed
   Content-Transfer-Encoding: 8bit

   [ Message body was here ]
   --=_mime_boundary_--

   The Source-Port field definition is given by [RFC6692]

   In the final MIME entity, the local-parts of To and From addresses
   are reported unredacted.  Since we know that the local parts are PII,
   we can reduce the privacy risk by redacting them.  In the example,
   the report generator could have replaced "users" with "lRLxexey" and
   "author" with "RT47aVey" throughout the entity.

   If the body of the message is not included, the last MIME entity
   would have "Content-Type: text/rfc822-headers" instead of message/
   rfc822.

Appendix B.  Change Log {change-log}

   [RFC Editor: Please remove this section prior to publication.]

B.1.  00 to 01

   *  Replace references to RFC7489 with references to I-D.ietf-dmarc-
      dmarcbis.

   *  Replace the 2nd paragraph in the Introduction with the text
      proposed by Ned for Ticket #55, which enjoys some consensus:
      https://mailarchive.ietf.org/arch/msg/dmarc/
      HptVyJ9SgrfxWRbeGwORagPrhCw
      (https://mailarchive.ietf.org/arch/msg/dmarc/
      HptVyJ9SgrfxWRbeGwORagPrhCw)

   *  Strike a spurious sentence about criticality of feedback, which
      was meant for feedback in general, not failure reports.  In fact,
      failure reports are not critical to establishing and maintaining
      accurate authentication deployments.  Still attributable to Ticket
      #55.

   *  Remove the content of section "Verifying External Destinations"
      and refer to I-D.ietf-dmarc-aggregate-reporting.

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   *  Remove the content of section "Security Considerations" and refer
      to I-D.ietf-dmarc-dmarcbis.

   *  Slightly tweak the wording of the example in Appendix A.1 so that
      it makes sense standing alone.

   *  Remove the sentence containing "must include any URI(s)", as the
      issue arose <eref
      target="https://mailarchive.ietf.org/arch/msg/dmarc/
      mFk0qiTCy8tzghRvcxus01W_Blw"/>.

   *  Add paragraph in Security Considerations, noting that note that
      Organizational Domains are only an approximation...

   *  Add a Transport section, mentioning DMARC conformance and failure
      report mail loops (Ticket #28).

B.2.  01 to 02

   *  Add a sentence to make clear that counting failures is not the
      aim.

B.3.  02 to 03

   *  Updated references.

B.4.  03 to 04

   *  Add an example report.

   *  Remove the old Acknowledgements section.

   *  Add a IANA Consideration section

B.5.  04 to 05

   *  Convert to markdown

   *  Remove irrelevant material.

B.6.  05 to 06

   *  A Vesely was incorrectly removed from list of document editors.
      Corrected.

   *  Added Terminology section with recoomended boilerplate re:
      RFC2119.

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B.7.  06 to 07

   *  Reduce Terminology section

   *  minor nits

B.8.  07 to 08

   *  Specify what detailed information a report contains, in the 1st
      paragraph of Section 2

   *  A couple of typos

B.9.  08 to 09

   *  Replace &lt; with < and &gt; with > in Appendix B

B.10.  09 to 10

   *  Add an informative section about other failure reports (DKIM, SPF)

B.11.  10 to 11

   *  Remove appendix with redundant examples - pull request by Daniel
      K.

B.12.  11 to 12

   *  Reference Terminology in [I-D.ietf-dmarc-dmarcbis]
   *  Expand the Verifying External Destinations section and reference
      [I-D.ietf-dmarc-aggregate-reporting]

B.13.  12 to 13

   *  Update references to numbered sections of
      [I-D.ietf-dmarc-dmarcbis] and [I-D.ietf-dmarc-aggregate-reporting]
   *  Clarify potential information disclosures when failure reports are
      sent
   *  Minor edits for readability and clarity

B.14.  13 to 14

   *  In the introduction (last paragraph) mention that the purpose is
      twofold, debug and anti-abuse.
   *  In Section 2 (2nd paragraph) clarify that failure reports allow
      better determining the failure reason.

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B.15.  14 to 15

   *  Expanded Privacy Considerations section as discussed on list.
   *  Add tentative IANA Consideration subsections.

B.16.  15 to 16

   *  Qualification of RFCs 6651/2 in Section 3.
   *  Spell "Auth-Failure" at bullet 3 of Section 4.
   *  Cite RFC 6590 when mentioning redaction.
   *  s/using the wrong sending path/failing authentication/.
   *  Remove unnecessary IANA Considerations.

B.17.  16 to 17

   *  Remove the last paragraph of Secority Considerations.

B.18.  17 to 18

   *  Reword the first purpose (Intro) and cite aggregate-reporting.
   *  Forward reference to Privacy Consideration.
   *  s/fo=/"fo"/, /ruf=/ruf/, /urls/URIs/.
   *  Specify parent registry in IANA Considerations.

B.19.  18 to 19

   *  Remove the term "scalable" from Abstract and Introduction.
   *  s/Sender Domain/Domain Owner/.
   *  Reference to dmarcbis, section 3.2 on its own line.
   *  Remove the phrase (sometimes referred to as "forensic reports").
   *  Note that Domain Owner can use dot-forward to not decalre
      consumer.
   *  Mention we could have encrypted the example.
   *  Don't mention MX.

B.20.  19 to 20

   *  Replace "dot-forward" with a periphrasis to downplay final
      destination.

B.21.  20 to 21

   *  Move the last paragraph of Section 2 to Security Considerations.
   *  Explicitly say we obsolete 7489 and update 6591 in the abstract.
   *  Reword "Without this check, a bad actor ..." in Section 5.
   *  Fix IANA request.
   *  Mention RFC 6591 in Terminology (Section 1.1).

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B.22.  21 to 22

   *  Reword obsoleting sentence in the abstract and move it to
      Section 1.2.

B.23.  22 to 23

   *  Merge Med's pull request

B.24.  23 to 24

   *  "Defang" issue.
   *  Avoid using "defined by" twice (Section 2, paragraph 5).
   *  Fix the normative part of rate-limiting (Section 2, paragraph 6).
   *  Recommend (non-2119) to rate limit (Section 5.1, paragraph 2).
   *  Reference RFC 5322 (Section 4, bullet 2).

Authors' Addresses

   Steven M Jones
   DMARC.org
   Email: smj@dmarc.org

   Alessandro Vesely
   Tana
   Email: vesely@tana.it

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