Resolution of the Sender Policy Framework (SPF) and Sender ID Experiments
RFC 6686

Internet Engineering Task Force (IETF)                      M. Kucherawy
Request for Comments: 6686                                     Cloudmark
Category: Informational                                        July 2012
ISSN: 2070-1721

            Resolution of the Sender Policy Framework (SPF)
                       and Sender ID Experiments

Abstract

   In 2006, the IETF published a suite of protocol documents comprising
   the Sender Policy Framework (SPF) and Sender ID: two proposed email
   authentication protocols.  Both of these protocols enable one to
   publish, via the Domain Name System, a policy declaring which mail
   servers were authorized to send email on behalf of the domain name
   being queried.  There was concern that the two would conflict in some
   significant operational situations, interfering with message
   delivery.

   The IESG required all of these documents (RFC 4405, RFC 4406, RFC
   4407, and RFC 4408) to be published as Experimental RFCs and
   requested that the community observe deployment and operation of the
   protocols over a period of two years from the date of publication to
   determine a reasonable path forward.

   After six years, sufficient experience and evidence have been
   collected that the experiments thus created can be considered
   concluded.  This document presents those findings.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6686.

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RFC 6686                SPF/Sender ID Experiments              July 2012

Copyright Notice

   Copyright (c) 2012 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................2
   2. Definitions .....................................................3
   3. Evidence of Deployment ..........................................3
      3.1. DNS Resource Record Types ..................................3
      3.2. Implementations ............................................5
      3.3. The SUBMITTER SMTP Extension ...............................6
   4. Evidence of Differences .........................................7
   5. Analysis ........................................................7
   6. Conclusions .....................................................8
   7. Security Considerations .........................................9
   8. References ......................................................9
      8.1. Normative References .......................................9
      8.2. Informative References .....................................9
   Appendix A. Background on the RRTYPE Issue ........................10
   Appendix B. Acknowledgments .......................................11

1.  Introduction

   In April 2006, the IETF published the [SPF] and Sender ID email
   authentication protocols, the latter consisting of three documents
   ([SUBMITTER], [SENDER-ID], and [PRA]).  Both of these protocols
   enable one to publish, via the Domain Name System, a policy declaring
   which mail servers are authorized to send email on behalf of the
   selected domain name.

   Consensus did not clearly support one protocol over the other, and
   there was significant concern that the two would conflict in some
   significant operational situations, interfering with message
   delivery.  The IESG required the publication of all of these
   documents as Experimental, and requested that the community observe

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