Domain-based Message Authentication, Reporting, and Conformance (DMARC) Failure Reporting
draft-ietf-dmarc-failure-reporting-13

DMARC                                                      S. Jones (ed)
Internet-Draft                                                 DMARC.org
Obsoletes: 7489 (if approved)                             A. Vesely (ed)
Updates: 6591 (if approved)                                         Tana
Intended status: Standards Track                           11 April 2025
Expires: 13 October 2025

Domain-based Message Authentication, Reporting, and Conformance (DMARC)
                           Failure Reporting
                 draft-ietf-dmarc-failure-reporting-13

Abstract

   Domain-based Message Authentication, Reporting, and Conformance
   (DMARC) is a scalable 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.

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 October 2025.

Copyright Notice

   Copyright (c) 2025 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.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components

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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  DMARC Failure Reports . . . . . . . . . . . . . . . . . . . .   3
   3.  Other Failure Reports . . . . . . . . . . . . . . . . . . . .   4
   4.  Reporting Format Update . . . . . . . . . . . . . . . . . . .   4
   5.  Verifying External Destinations . . . . . . . . . . . . . . .   5
     5.1.  Transport . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   6
     6.1.  Feedback Report Header Fields Registry Update . . . . . .   6
   7.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
     7.1.  Data Exposure Considerations  . . . . . . . . . . . . . .   6
     7.2.  Report Recipients . . . . . . . . . . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   10. Informative References  . . . . . . . . . . . . . . . . . . .   8
   Appendix A.  Example Failure Report . . . . . . . . . . . . . . .   9
   Appendix B.  Change Log {change-log}  . . . . . . . . . . . . . .  12
     B.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  12
     B.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  13
     B.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  13
     B.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  13
     B.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  13
     B.6.  05 to 06  . . . . . . . . . . . . . . . . . . . . . . . .  14
     B.7.  06 to 07  . . . . . . . . . . . . . . . . . . . . . . . .  14
     B.8.  07 to 08  . . . . . . . . . . . . . . . . . . . . . . . .  14
     B.9.  08 to 09  . . . . . . . . . . . . . . . . . . . . . . . .  14
     B.10. 09 to 10  . . . . . . . . . . . . . . . . . . . . . . . .  14
     B.11. 10 to 11  . . . . . . . . . . . . . . . . . . . . . . . .  14
     B.12. 11 to 12  . . . . . . . . . . . . . . . . . . . . . . . .  14
     B.13. 12 to 13  . . . . . . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

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 scalable mechanism by which a
   mail-originating organization can express domain-level policies and

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   preferences for message validation, disposition, and reporting, that
   a mail-receiving organization can use 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.  They are meant to aid in cases where a Domain Owner is
   unable to detect why failures that were reported in aggregate form
   occurred.  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.

1.1.  Terminology

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

   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.

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 the 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.
   Whether the failure is due to an infrastructure problem or the
   message is inauthentic, failure reports also provide more information
   about the failed message than is available in an aggregate report.

   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.

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

   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.

   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)

3.  Other Failure Reports

   This document only describes DMARC failure reports.  DKIM failure
   reports [RFC6651] and SPF failure reports [RFC6652] are described in
   separate documents.  A Mail Receiver generating a DMARC failure
   report may or may not also issue a failure report specific to the
   failed authentication mechanism, according to its policy.

4.  Reporting Format Update

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

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   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)

   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]):

   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, 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.

   Without this check, a bad actor could publish a DMARC Policy Record
   that requests that failure reports be sent to an external
   destination, then deliberately send messages that will generate
   failure reports as a form of abuse.  Or, a Domain Owner could

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   incorrectly publish a DMARC Policy Record with an external
   destination for failure reports, forcing the external destination to
   deal with unwanted messages and potential privacy issues.

   Therefore, 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.`

5.1.  Transport

   Email streams carrying DMARC failure reports SHOULD be DMARC aligned.

   Reporters MAY rate limit 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 to refer to this document.

7.  Privacy Considerations

   This section discusses issues specific to private data that may be
   included in the DMARC reporting functions.

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 [RFC6591] format used for failed-message
   reporting supports redaction, failed-message reporting is capable of
   exposing the entire message to the Report Consumer.

   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 messages
   mistakenly or accidentally using the wrong sending domain.

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   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 contracts with 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
   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.

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].

   In addition, note that Organizational Domains are only an
   approximation to actual domain ownership.  Therefore, reports may be
   sent to someone unrelated to the actual sender or Domain Owner.  That
   makes considerations in Section 7.1 all the more relevant.

9.  Normative References

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   [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>.

   [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>.

   [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

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   [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>.

Appendix A.  Example Failure Report

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

   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.

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   --=_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
   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;

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     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==
   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])

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     (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
   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]

   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)

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   *  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.

   *  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.

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B.6.  05 to 06

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

   *  Added Terminology section with recoomended boilerplate re:
      RFC2119.

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

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Authors' Addresses

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

   Alessandro Vesely
   Tana
   Email: vesely@tana.it

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