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 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 http://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 August 2, 2014. Copyright Notice Copyright (c) 2014 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 (http://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 extracted from this document must 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. Kucherawy Expires August 2, 2014 [Page 1] 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 Kucherawy Expires August 2, 2014 [Page 2] Internet-Draft Email Auth Status Codes January 2014 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 Kucherawy Expires August 2, 2014 [Page 3] 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 Kucherawy Expires August 2, 2014 [Page 4] Internet-Draft Email Auth Status Codes January 2014 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 Kucherawy Expires August 2, 2014 [Page 5]