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Domain-based Message Authentication, Reporting, and Conformance (DMARC) Failure Reporting
draft-ietf-dmarc-failure-reporting-05

Document Type Active Internet-Draft (dmarc WG)
Author Steven M Jones
Last updated 2022-08-21
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draft-ietf-dmarc-failure-reporting-05
DMARC                                                      S. Jones (ed)
Internet-Draft                                                 DMARC.org
Obsoletes: 7489 (if approved)                             21 August 2022
Updates: 6591 (if approved)                                             
Intended status: Standards Track                                        
Expires: 22 February 2023

Domain-based Message Authentication, Reporting, and Conformance (DMARC)
                           Failure Reporting
                 draft-ietf-dmarc-failure-reporting-05

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 22 February 2023.

Copyright Notice

   Copyright (c) 2022 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
   2.  Failure Reports . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Reporting Format Update . . . . . . . . . . . . . . . . . . .   4
   4.  Verifying External Destinations . . . . . . . . . . . . . . .   5
     4.1.  Transport . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Feedback Report Header Fields Registry Update . . . . . .   5
   6.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   5
     6.1.  Data Exposure Considerations  . . . . . . . . . . . . . .   5
     6.2.  Report Recipients . . . . . . . . . . . . . . . . . . . .   6
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   6
   Appendix A.  Examples . . . . . . . . . . . . . . . . . . . . . .   7
     A.1.  Entire Domain, Monitoring Only, Per-Message Reports . . .   7
     A.2.  Per-Message Failure Reports Directed to Third Party . . .   8
   Appendix B.  Example Failure Report . . . . . . . . . . . . . . .   9
   Appendix C.  Change Log {change-log}  . . . . . . . . . . . . . .  13
     C.1.  00 to 01  . . . . . . . . . . . . . . . . . . . . . . . .  13
     C.2.  01 to 02  . . . . . . . . . . . . . . . . . . . . . . . .  14
     C.3.  02 to 03  . . . . . . . . . . . . . . . . . . . . . . . .  14
     C.4.  03 to 04  . . . . . . . . . . . . . . . . . . . . . . . .  14
     C.5.  04 to 05  . . . . . . . . . . . . . . . . . . . . . . . .  14
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  14

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
   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

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   unable to detect why failures reported in aggregate form did occur.
   It is important to note these reports can contain either the header
   or the entire content of a failed message, which in turn may contain
   personally identifiable information, which should be considered when
   deciding whether to generate such reports.

2.  Failure Reports

   Failure reports can supply more detailed information about messages
   that failed to authenticate, enabling the Domain Owner to determine
   exactly what might be causing those specific failures.

   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 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 3.

   The destination(s) and nature of the reports are defined by the "ruf"
   and "fo" tags as defined in Section 6.3 of [I-D.ietf-dmarc-dmarcbis].

   Where multiple URIs are selected to receive failure reports, the
   report generator MUST make an attempt to deliver to each of them.
   External destinations MUST be verified, see Section 4.  Report
   generators MUST NOT consider ruf= tags in records having a "psd=y"
   tag, unless there are specific agreements between the interested
   parties.

   An obvious consideration is the denial-of-service attack that can be
   perpetrated by an attacker who sends numerous messages purporting to
   be from the intended victim Domain Owner but that fail both SPF and
   DKIM; this would cause participating Mail Receivers to send failure
   reports to the Domain Owner or its delegate in potentially huge
   volumes.  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

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   not to count each and every failure, but rather to report different
   failure paths.  Various pruning techniques are possible, including
   the following:

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

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

3.  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)

   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:

   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

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   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.

4.  Verifying External Destinations

   If the target domain of a mailto address of a ruf= tag is not the
   same as the DMARC record domain where the tag was found, the report
   generator MUST verify that the target domain acknowledges sending
   those reports; the procedure is described in Section 3 of
   [I-D.ietf-dmarc-aggregate-reporting].

4.1.  Transport

   Email streams carrying DMARC failure reports SHOULD provide 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.

5.  IANA Considerations

5.1.  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.

6.  Privacy Considerations

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

6.1.  Data Exposure Considerations

   Failed-message reporting provides message-specific details pertaining
   to authentication failures.  Individual reports can contain message
   content as well as trace header fields.  Domain Owners are able to
   analyze individual reports and attempt to determine root causes of
   authentication mechanism failures, gain insight into
   misconfigurations or other problems with email and network
   infrastructure, or inspect messages for insight into abusive
   practices.

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   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 recipient.

   Domain Owners requesting reports will receive information about mail
   claiming to be from them, which includes mail that was not, in fact,
   from them.  Information about the final destination of mail where it
   might otherwise be obscured by intermediate systems will therefore be
   exposed.

   When message-forwarding arrangements exist, Domain Owners requesting
   reports will also receive information about mail forwarded to domains
   that were not originally part of their messages' recipient lists.
   This means that destination domains previously unknown to the Domain
   Owner may now become visible.

6.2.  Report Recipients

   A DMARC record can specify that reports should be sent to an
   intermediary operating on behalf of the Domain Owner.  This is done
   when the Domain Owner contracts with an entity to monitor mail
   streams for abuse and performance issues.  Receipt by third parties
   of such data may or may not be permitted by the Mail Receiver's
   privacy policy, terms of use, or other similar governing document.
   Domain Owners and Mail Receivers should both review and understand if
   their own internal policies constrain the use and transmission of
   DMARC reporting.

   Some potential exists for report recipients to perform traffic
   analysis, making it possible to obtain metadata about the Receiver's
   traffic.  In addition to verifying compliance with policies,
   Receivers need to consider that before sending reports to a third
   party.

7.  Security Considerations

   Considerations discussed in Section 11 of [I-D.ietf-dmarc-dmarcbis]
   apply.

   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 6.1 all the more relevant.

8.  Normative References

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   [I-D.ietf-dmarc-aggregate-reporting]
              Brotman, A., "DMARC Aggregate Reporting", Work in
              Progress, Internet-Draft, draft-ietf-dmarc-aggregate-
              reporting-05, 20 April 2022,
              <https://www.ietf.org/archive/id/draft-ietf-dmarc-
              aggregate-reporting-05.txt>.

   [I-D.ietf-dmarc-dmarcbis]
              Herr, T. M. and J. Levine, "Domain-based Message
              Authentication, Reporting, and Conformance (DMARC)", Work
              in Progress, Internet-Draft, draft-ietf-dmarc-dmarcbis-15,
              28 July 2022, <https://www.ietf.org/archive/id/draft-ietf-
              dmarc-dmarcbis-15.txt>.

   [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>.

Appendix A.  Examples

   This section presents some examples related to the use of DMARC
   reporting functions.

A.1.  Entire Domain, Monitoring Only, Per-Message Reports

   The owners of the domain "example.com" have deployed SPF and DKIM on
   their messaging infrastructure.  As described in, Appendix B.2.1 of
   [I-D.ietf-dmarc-aggregate-reporting] they have used the aggregate
   reporting to discover some messaging systems that had not yet
   implemented DKIM correctly.  However, they are still seeing periodic
   authentication failures.  In order to diagnose these intermittent
   problems, they wish to request per-message failure reports when
   authentication failures occur.

   Many Receivers will not honor such a request, but the Domain Owner
   feels that any reports it does receive will be helpful enough to
   justify publishing this record.

   The Domain Owner accomplishes this by adding the following to its
   policy record:

   Failure reports should be sent via email to the address "auth-
   reports@example.com" ("ruf=mailto:auth-reports@example.com")

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   The updated DMARC policy record might look like this when retrieved
   using a common command-line tool (the output shown would appear on a
   single line but is wrapped here for publication):

   % dig +short TXT _dmarc.example.com.
     "v=DMARC1; p=none; rua=mailto:dmarc-feedback@example.com;
      ruf=mailto:auth-reports@example.com"

   To publish such a record, the DNS administrator for the Domain Owner
   might create an entry like the following in the appropriate zone file
   (following the conventional zone file format):

    DMARC record for the domain example.com

    _dmarc  IN TXT ( "v=DMARC1; p=none; "
                     "rua=mailto:dmarc-feedback@example.com; "
                     "ruf=mailto:auth-reports@example.com" )

A.2.  Per-Message Failure Reports Directed to Third Party

   The Domain Owner from the previous example is maintaining the same
   policy but now wishes to have a third party receive and process the
   per-message failure reports.  Again, not all Receivers will honor
   this request, but those that do may implement additional checks to
   validate that the third party wishes to receive the failure reports
   for this domain.

   The Domain Owner needs to alter its policy record from {#entire-
   domain-monitoring-only-per-message-reports} as follows:

   Per-message failure reports should be sent via email to the address
   "auth-reports@thirdparty.example.net" ("ruf=mailto:auth-
   reports@thirdparty.example.net")

   The DMARC policy record might look like this when retrieved using a
   common command-line tool (the output shown would appear on a single
   line but is wrapped here for publication):

   % dig +short TXT _dmarc.example.com.
     "v=DMARC1; p=none; rua=mailto:dmarc-feedback@example.com;
      ruf=mailto:auth-reports@thirdparty.example.net"

   To publish such a record, the DNS administrator for the Domain Owner
   might create an entry like the following in the appropriate zone file
   (following the conventional zone file format):

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   ; DMARC record for the domain example.com

    _dmarc IN TXT ( "v=DMARC1; p=none; "
                     "rua=mailto:dmarc-feedback@example.com; "
                     "ruf=mailto:auth-reports@thirdparty.example.net" )

   Because the address used in the "ruf" tag is outside the
   Organizational Domain in which this record is published, conforming
   Receivers will implement additional checks as described in Section 4
   of this document.  In order to pass these additional checks, the
   third party will need to publish an additional DNS record as follows:

   Given the DMARC record published by the Domain Owner at
   "_dmarc.example.com", the DNS administrator for the third party will
   need to publish a TXT resource record at
   "example.com._report._dmarc.thirdparty.example.net" with the value
   "v=DMARC1;"

   The resulting DNS record might look like this when retrieved using a
   common command-line tool (the output shown would appear on a single
   line but is wrapped here for publication):

   % dig +short TXT example.com._report._dmarc.thirdparty.example.net
     "v=DMARC1;"

   To publish such a record, the DNS administrator for example.net might
   create an entry like the following in the appropriate zone file
   (following the conventional zone file format):

    zone file for thirdparty.example.net
   ; Accept DMARC failure reports on behalf of example.com

   example.com._report._dmarc   IN   TXT    "v=DMARC1;"

   Intermediaries and other third parties should refer to Section 4 for
   the full details of this mechanism.

Appendix B.  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;

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     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 &lt;DMARC@gen.example&gt;
   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: &lt;20220719055748.4AE9D403CC@gen.example&gt;

   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
   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

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   --=_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 &lt;x@gen.example&gt;; 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 &lt;x@gen.example&gt;; 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==
   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 &lt;users@forwarder.example&gt;; Tue, 19 Jul 2022 07:57:41 +0200 (CEST)

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   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 &lt;author@consumer.example&gt;
   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: &lt;2431dc66-b010-c9cc-4f2b-a1f889f8bdb4@consumer.example&gt;
   Date: Tue, 19 Jul 2022 07:57:33 +0200
   List-Id: &lt;users.forwarder.example&gt;
   List-Post: &lt;mailto:users@forwarder.example&gt;
   List-Help: &lt;mailto:users+help@forwarder.example&gt;
   List-Subscribe: &lt;mailto:users+subscribe@forwarder.example&gt;
   List-Unsubscribe: &lt;mailto:users+unsubscribe@forwarder.example&gt;
   List-Owner: &lt;mailto:users+owner@forwarder.example&gt;
   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 &lt;author@consumer.example&gt;
   In-Reply-To: &lt;20220718102753.0f6d9dde.cel@example.com&gt;
   Content-Type: text/plain; charset=UTF-8; format=flowed
   Content-Transfer-Encoding: 8bit

   [ Message body was here ]

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   --=_mime_boundary_--

   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 C.  Change Log {change-log}

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

C.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.

   *  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).

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C.2.  01 to 02

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

C.3.  02 to 03

   *  Updated references.

C.4.  03 to 04

   *  Add an example report.

   *  Remove the old Acknowledgements section.

   *  Add a IANA Consideration section

C.5.  04 to 05

   *  Convert to markdown

   *  Remove irrelevant material.

Author's Address

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

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