MARF Working Group                                               J. Falk
Internet-Draft                                               Return Path
Updates: 5965 (if approved)                            M. Kucherawy, Ed.
Intended status: Standards Track                               Cloudmark
Expires: June 30, 2012                                 December 28, 2011

 Creation and Use of Email Feedback Reports: An Applicability Statement
                  for the Abuse Reporting Format (ARF)


   RFC 5965 defines an extensible, machine-readable format intended for
   mail operators to report feedback about received email to other
   parties.  This document describes common methods for utilizing this
   format for abuse reporting.  Mailbox Providers of any size, mail
   sending entities, and end users can use these methods as a basis to
   create procedures that best suit them.

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
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 30, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   ( in effect on the date of
   publication of this document.  Please review these documents
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   to this document.  Code Components extracted from this document must

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

1.  Introduction

   The Abuse Reporting Format (ARF) was initially developed for two very
   specific use cases.  Initially, it was intended to be used for
   reporting feedback between large email operators, or from large email
   operators to end user network access operators, any of whom could be
   presumed to have automated abuse-handling systems.  Secondarily, it
   is used by those same large mail operators to send those same reports
   to other entities, including those involved in sending bulk email for
   commercial purposes.  In either case, the reports would be triggered
   by direct end user action such as clicking on a "report spam" button
   in their email client.

   Though other uses for the format defined in [RFC5965] have been
   discussed (and may be documented similarly in the future), abuse
   remains the primary application.

   The purpose for reporting abusive messages is to stop recurrences.
   The methods described in this document focus on automating abuse
   reporting as much as practical, so as to minimize the work of a
   site's abuse team.  There are further reasons why abuse feedback
   generation is worthwhile, such as instruction of mail filters or
   reputation trackers, or to initiate investigations of particularly
   egregious abuses.  These other applications are not discussed in this

   Further introduction to this topic may be found in [RFC6449].

2.  Definitions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119], and are
   intended to replace the Requirement Levels described in Section 3.3
   of [RFC2026].

   Some of the terminology used in this document is taken from

   "Mailbox Provider" refers to an organization that accepts, stores,
   and offers access to [RFC5322] messages ("email messages") for end
   users.  Such an organization has typically implemented SMTP

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   ([RFC5321]), and might provide access to messages through IMAP
   ([RFC3501]), POP ([RFC1939]), a proprietary interface designed for
   HTTP ([RFC2616]), or a proprietary protocol.

3.  Applicability Statement

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

   NOTE TO IESG: This document is part of the experiment to reintroduce
   Applicability Statements, as defined in Section 3.2 of [RFC2026], to
   the Applications Area.

4.  Discussion

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

   This document is being discussed within the IETF MARF Working Group,
   on the mailing list.

5.  Solicited and Unsolicited Reports

   The original application of [RFC5965], and still by far the most
   common, is when two mail systems make a private agreement to exchange
   abuse reports, usually reports due to recipients manually reporting
   messages as spam.  We refer to these as solicited reports.

   Other uses for ARF involve reports sent between parties that don't
   know each other, with the recipient address typically being
   abuse@domain (see [RFC2142]), looked up via WHOIS, or using other
   heuristics.  The reports may be manual, or automated due to hitting
   spam traps, scored high by spam filters, or anything else that the
   sender of the report considers to merit an abuse report.

   In either case, where an abusive message is signed using a domain-
   level authentication technology such as DKIM ([RFC6376]) or SPF
   ([RFC4408]), the domain that has been verified by the authentication
   mechanism is likely a reasonable candidate for receiving feedback
   about the message.

6.  Creating and Sending Complaint-Based Solicited Reports

   1.  A Mailbox Provider receives reports of abusive or unwanted mail
       from its users, most often by providing a "report spam" button
       (or similar nomenclature) in the MUA.  The method of transferring

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       this message and any associated metadata from the MUA to the
       Mailbox Provider's ARF processing system is not defined by any
       standards document, but is discussed further in Section 3.2 of
       [RFC6449].  Policy concerns related to the collection of this
       data are discussed in Section 3.4 of that document.
   2.  The Mailbox Provider SHOULD process the reports to improve its
       spam filtering systems.  The design of these systems is discussed
       in [RFC2505] and elsewhere.
   3.  The Mailbox Provider SHOULD send reports to relevant parties who
       have requested to receive such reports.  The reports MUST be
       formatted per [RFC5965], and transmitted as an email message
       ([RFC5322]), typically using SMTP ([RFC5321]).  The process
       whereby such parties may request the reports is discussed in
       Section 3.5 of [RFC6449].
   4.  The reports SHOULD use "Feedback-Type: abuse", but MAY use other
       types as appropriate.  However, the Mailbox Provider generating
       the reports SHOULD NOT assume that the operator receiving the
       reports will treat different Feedback-Types differently.
   5.  The reports SHOULD include the following optional fields whenever
       practical: Original-Mail-From, Arrival-Date, Source-IP, Original-
       Rcpt-To.  Other optional fields MAY be included, as the
       implementer feels is appropriate.
   6.  Ongoing maintenance of an ARF processing system is discussed in
       Section 3.6 of [RFC6449].

7.  Receiving and Processing Complaint-Based Solicited Reports

   1.  At the time this document is being written, for the use cases
       described here, mail operators need to proactively request a
       stream of ARF reports from Mailbox Providers.  Recommendations
       for preparing to make that request are discussed in Section 4.1
       of [RFC6449].
   2.  Mail operators MUST be prepared to receive reports formatted per
       [RFC5965] as email messages ([RFC5322]) over SMTP ([RFC5321]).
       These and other types of email messages that may be received are
       discussed in Section 4.2 of [RFC6449].
   3.  Mail operators SHOULD utilize an automated system to receive and
       process these reports, as discussed in Section 4.4 of [RFC6449].
   4.  That system MUST accept all Feedback-Types defined in [RFC5965]
       or extensions to it, but implementers SHOULD NOT assume that
       Mailbox Providers will make use of any Feedback-Type other than
       "abuse".  Additional logic may be required to separate different
       types of abuse reports after receipt.
   5.  Implementers SHOULD NOT expect all Mailbox Providers to include
       the same optional fields.

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   6.  Actions that mail operators might take upon receiving a report
       (or multiple reports) are discussed in Section 4.3 of [RFC6449].

8.  Generating and Handling Unsolicited Reports

   Systems that generate unsolicited reports SHOULD ensure that the
   criteria used to decide what messages to report accurately identify
   messages that the generating entity believes in good faith are
   abusive.  Criteria might include direct complaint submissions from
   MUAs, reports triggered by mail sent to "spam trap" or "honeypot"
   addresses, reports of authentication failures, and virus reports.
   (These applications might be described in future IETF documents.)
   Systems SHOULD NOT report all mail sent from a particular sender
   merely because some of it is determined to be abusive.

   Senders SHOULD send reports to recipients that are both responsible
   for the messages and are able to do something about them, and SHOULD
   NOT send reports to recipients that are uninvolved or only
   peripherally involved.  For example, they SHOULD NOT send reports to
   the operator of every Autonomous System in the path between the
   apparent originating system and the operator generating the report.

   Recipients of unsolicited ARF reports SHOULD, in general, handle them
   the same way as any other abuse reports.  Lacking knowledge about the
   sender of the report, they SHOULD separate valid from invalid reports
   by, for example, looking for references to IP ranges, domains, and
   mailboxes for which the recipient organization is responsible in the
   copy of the reported message, and by correlating multiple reports of
   similar messages to identify bulk senders.

   Some large messaging service providers specifically request that
   abuse reports be sent to them in ARF format.  Experience of systems
   that send abuse reports in ARF format suggests that even recipient
   systems that haven't asked for ARF format reports handle them at
   least as well as any other format such as plain text, with or without
   a copy of the message attached.

9.  IANA Considerations

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

   This document has no IANA actions.

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10.  Security Considerations

   Implementers are strongly urged to review, at a minimum, the Security
   Considerations sections of [RFC5965] and [RFC6449].

11.  Acknowledgements

   The author and editor wish to thank John Levine and Alessandro Vesely
   for their contributions to this memo.

   All of the Best Practices referenced by this document are found in
   [RFC6449], written within the Collaboration Committee of the
   Messaging Anti-Abuse Working Group (MAAWG) -- which is described
   further in [RFC6449].

   Finally, the original author wishes to thank the doctors and staff at
   the University of Texas MD Anderson Cancer Center for doing what they

12.  References

12.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5321]  Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
              October 2008.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              October 2008.

   [RFC5598]  Crocker, D., "Internet Mail Architecture", RFC 5598,
              July 2009.

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

12.2.  Informative References

   [RFC1939]  Myers, J. and M. Rose, "Post Office Protocol - Version 3",
              STD 53, RFC 1939, May 1996.

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

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              FUNCTIONS", RFC 2142, May 1997.

   [RFC2505]  Lindberg, G., "Anti-Spam Recommendations for SMTP MTAs",
              BCP 30, RFC 2505, February 1999.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.

              4rev1", RFC 3501, March 2003.

   [RFC4408]  Wong, M. and W. Schlitt, "Sender Policy Framework (SPF)
              for Authorizing Use of Domains in E-Mail, Version 1",
              RFC 4408, April 2006.

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

   [RFC6449]  Falk, J., "Complaint Feedback Loop Operational
              Recommendations", RFC 6449, November 2011.

Authors' Addresses

   J.D. Falk
   Return Path
   100 Mathilda Street, Suite 100
   Sunnyvale, CA  94089


   M. Kucherawy (editor)
   128 King St., 2nd Floor
   San Francisco, CA  94107


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