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
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document authors. All rights reserved.
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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
Kucherawy Informational [Page 2]
RFC 6686 SPF/Sender ID Experiments July 2012
deployment and operation of the protocols over a period of two years
from the date of publication in order to determine a reasonable path
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