Network Working Group M. Kucherawy
Internet-Draft January 29, 2014
Intended status: Informational
Expires: August 2, 2014
Email Authentication Status Codes
draft-kucherawy-email-auth-codes-00
Abstract
There is at present no way to return a status code to an email client
that indicates a message is being rejected or deferred specifically
because of email authentication failures. This document registers
codes for this purpose.
Status of This Memo
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Internet-Draft Email Auth Status Codes January 2014
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. New Status Codes . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. DKIM Failures Code . . . . . . . . . . . . . . . . . . . . 3
2.2. SPF Failures Code . . . . . . . . . . . . . . . . . . . . . 4
3. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
5. Normative References . . . . . . . . . . . . . . . . . . . . . 4
Appendix A. Notes to the RFC Editor . . . . . . . . . . . . . . . 4
Appendix B. Acknowledgments . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
[RFC3463] introduced Enhanced Mail System Status Codes, and [RFC5248]
created an IANA registry for these.
[RFC6376] and [RFC4408] introduced, respectively, DomainKeys
Identified Mail and Sender Policy Framework, two protocols for
conducting email authentication.
The current set of enhanced status codes does not include any code
for indicating that a message is being rejected or deferred due to
negative results in either of these two mechanisms. This document
introduces an enhanced status code for reporting those cases to
clients.
2. New Status Codes
The following new status codes are defined:
2.1. DKIM Failures Code
Code: X.7.19
Sample Text: DKIM signature failed to validate
Associated basic status code: 5
Description: This status code is returned when a message
contained a valid DKIM signature, but the
signature failed to validate, contrary
to local policy requirements.
Reference: [this document]
Submitter: M. Kucherawy
Change controller: IESG
Code: X.7.20
Sample Text: DKIM signature absent
Associated basic status code: 5
Description: This status code is returned when a message
contained no DKIM signature, contrary to
local policy requirements.
Reference: [this document]
Submitter: M. Kucherawy
Change controller: IESG
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Internet-Draft Email Auth Status Codes January 2014
2.2. SPF Failures Code
Code: X.7.21
Sample Text: SPF validation failed
Associated basic status code: 5
Description: This status code is returned when a message
failed an SPF check, contrary to local
policy requirements.
Reference: [this document]
Submitter: M. Kucherawy
Change controller: IESG
3. Security Considerations
Use of these codes reveals local policy with respect to email
authentication, which can be useful information to actors attempting
to deliver undesirable mail. It should be noted that there is no
specific obligation to use these codes; if an operator wishes not to
reveal this aspect of local policy, it can continue using a generic
result such as 5.7.7 or even 5.7.0.
4. IANA Considerations
Registration of two new enhanced status codes, for addition to the
SMTP Enhanced Status Codes Registry, can be found in Section 2.
5. Normative References
[RFC3463] Vaudreuil, G., "Enhanced Mail System Status Codes",
RFC 3463, January 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.
[RFC5248] Hansen, T. and J. Klensin, "A Registry for SMTP Enhanced
Mail System Status Codes", BCP 138, RFC 5248, June 2008.
[RFC6376] Crocker, D., Hansen, T., and M. Kucherawy, "DomainKeys
Identified Mail (DKIM) Signatures", STD 76, RFC 6376,
September 2011.
Appendix A. Notes to the RFC Editor
[Please remove this section prior to publication.]
[RFC4408] is in the RFC Editor queue as of this writing. It will
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need to updated at some point.
Appendix B. Acknowledgments
[TBD]
Author's Address
Murray S. Kucherawy
270 Upland Drive
San Francisco, CA 94127
USA
EMail: superuser@gmail.com
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