draft-ietf-appsawg-email-auth-codes-02.txt   draft-ietf-appsawg-email-auth-codes-03.txt 
Network Working Group M. Kucherawy Network Working Group M. Kucherawy
Internet-Draft June 2, 2014 Internet-Draft June 26, 2014
Intended status: Informational Updates: 7208 (if approved)
Expires: December 4, 2014 Intended status: Standards Track
Expires: December 28, 2014
Email Authentication Status Codes Email Authentication Status Codes
draft-ietf-appsawg-email-auth-codes-02 draft-ietf-appsawg-email-auth-codes-03
Abstract Abstract
There is at present no way to return a status code to an email client 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 that indicates a message is being rejected or deferred specifically
because of email authentication failures. This document registers because of email authentication failures. This document registers
codes for this purpose. codes for this purpose.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 4, 2014. This Internet-Draft will expire on December 28, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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created an IANA registry for these. created an IANA registry for these.
[RFC6376] and [RFC7208] introduced, respectively, DomainKeys [RFC6376] and [RFC7208] introduced, respectively, DomainKeys
Identified Mail and Sender Policy Framework, two protocols for Identified Mail and Sender Policy Framework, two protocols for
conducting email authentication. Another common email acceptance conducting email authentication. Another common email acceptance
test is the reverse Domain Name System check on an email client's IP test is the reverse Domain Name System check on an email client's IP
address, as described in Section 3 of [RFC7001]. address, as described in Section 3 of [RFC7001].
The current set of enhanced status codes does not include any code The current set of enhanced status codes does not include any code
for indicating that a message is being rejected or deferred due to for indicating that a message is being rejected or deferred due to
local policy reasons related to either of these two mechanisms. This local policy reasons related to any of these mechanisms. This is
is potentially useful information to agents that need more than potentially useful information to agents that need more than
rudimentary handling information about the reason a message was rudimentary handling information about the reason a message was
rejected on receipt. This document introduces enhanced status codes rejected on receipt. This document introduces enhanced status codes
for reporting those cases to clients. for reporting those cases to clients.
2. Key Words 2. Key Words
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
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Associated basic status code: 5 Associated basic status code: 5
Description: This status code is returned when a message Description: This status code is returned when a message
did not contain a valid DKIM signature, did not contain a valid DKIM signature,
contrary to local policy requirements. contrary to local policy requirements.
(Note that this violates the advice of (Note that this violates the advice of
Section 6.1 of RFC6376.) Section 6.1 of RFC6376.)
Reference: [this document]; RFC6376 Reference: [this document]; RFC6376
Submitter: M. Kucherawy Submitter: M. Kucherawy
Change controller: IESG Change controller: IESG
Code: X.7.21 Code: X.7.21
Sample Text: No valid author DKIM signature found Sample Text: No valid author-aligned DKIM signature found
Associated basic status code: 5 Associated basic status code: 5
Description: This status code is returned when a message Description: This status code is returned when a message
did not contain a valid DKIM signature did not contain a valid DKIM signature
matching the domain(s) found in the From matching the domain(s) found in the From
header field, contrary to local policy header field, contrary to local policy
requirements. (Note that this violates the requirements. (Note that this violates the
advice of Section 6.1 of RFC6376.) advice of Section 6.1 of RFC6376.)
Reference: [this document]; RFC6376 Reference: [this document]; RFC6376
Submitter: M. Kucherawy Submitter: M. Kucherawy
Change controller: IESG Change controller: IESG
3.2. SPF Failure Codes 3.2. SPF Failure Codes
Code: X.7.22 Code: X.7.22
Sample Text: SPF validation failed Sample Text: SPF validation failed
Associated basic status code: 5 Associated basic status code: 5
Description: This status code is returned when a message Description: This status code is returned when a message
failed an SPF check, contrary to local completed an SPF check that produced a
policy requirements. "fail" result, contrary to local policy
requirements. Used in place of 5.7.1 as
described in Section 8.4 of RFC7208.
Reference: [this document]; RFC7208 Reference: [this document]; RFC7208
Submitter: M. Kucherawy Submitter: M. Kucherawy
Change controller: IESG Change controller: IESG
Code: X.7.23 Code: X.7.23
Sample Text: SPF validation error Sample Text: SPF validation error
Associated basic status code: 5 Associated basic status code: 4/5
Description: This status code is returned when evaluation Description: This status code is returned when evaluation
of SPF relative to an arriving message of SPF relative to an arriving message
resulted in an error. resulted in an error. Used in place of
4.4.3 or 5.5.2 as described in Sections
8.6 and 8.6 of RFC7208.
Reference: [this document]; RFC7208 Reference: [this document]; RFC7208
Submitter: M. Kucherawy Submitter: M. Kucherawy
Change controller: IESG Change controller: IESG
3.3. Reverse DNS Failure Code 3.3. Reverse DNS Failure Code
Code: X.7.24 Code: X.7.24
Sample Text: Reverse DNS validation failed Sample Text: Reverse DNS validation failed
Associated basic status code: 5 Associated basic status code: 5
Description: This status code is returned when an SMTP Description: This status code is returned when an SMTP
client's IP address failed a reverse DNS client's IP address failed a reverse DNS
validation check, contrary to local policy validation check, contrary to local policy
requirements. requirements.
Reference: [this document]; Section 3 of RFC 7001 Reference: [this document]; Section 3 of RFC7001
Submitter: M. Kucherawy Submitter: M. Kucherawy
Change controller: IESG Change controller: IESG
3.4. Multiple Authentication Failures Code 3.4. Multiple Authentication Failures Code
Code: X.7.25 Code: X.7.25
Sample Text: Multiple authentication checks failed Sample Text: Multiple authentication checks failed
Associated basic status code: 5 Associated basic status code: 5
Description: This status code is returned when a message Description: This status code is returned when a message
failed more than one message authentication failed more than one message authentication
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enhanced status code can be returned for a given exchange between enhanced status code can be returned for a given exchange between
client and server. However, an operator might decide to defer or client and server. However, an operator might decide to defer or
reject a message for a plurality of reasons. Clients receiving these reject a message for a plurality of reasons. Clients receiving these
codes need to consider that the failure reflected by one of these codes need to consider that the failure reflected by one of these
status codes might not reflect the only reason, or the most important status codes might not reflect the only reason, or the most important
reason, for non-acceptance of the message or command. reason, for non-acceptance of the message or command.
It is important to note that Section 6.1 of [RFC6376] discourages It is important to note that Section 6.1 of [RFC6376] discourages
special treatment of messages bearing no valid signature. There are special treatment of messages bearing no valid signature. There are
some operators that disregard this advice, a few of which go so far some operators that disregard this advice, a few of which go so far
as to require a valid Author Domain signature in order to accept the as to require a valid Author Domain signature (that is, one matching
the domain(s) in the From header field) in order to accept the
message. Moreover, some nascent technologies built atop SPF and DKIM message. Moreover, some nascent technologies built atop SPF and DKIM
depend on such authentications. This work does not endorse depend on such authentications. This work does not endorse
configurations that violate DKIM's recommendations, but rather configurations that violate DKIM's recommendations, but rather
acknowledges that they do exist and provides for improved acknowledges that they do exist and merely seeks to provide for
interoperability with such operators. improved interoperability with such operators.
A specific use case is mailing list software, which processes A specific use case is mailing list software, which processes
rejections in order to remove from the subscriber set those addresses rejections in order to remove from the subscriber set those addresses
that are no longer valid. There is a need in that case to that are no longer valid. There is a need in that case to
distinguish authentication failures verus indications that the distinguish authentication failures versus indications that the
recipient address is no longer valid. recipient address is no longer valid.
When multiple authentication methods fail, the SMTP server SHOULD use When multiple authentication methods fail, the SMTP server SHOULD use
the code that indicates multiple methods failed rather than only the the code that indicates multiple methods failed rather than only the
first one that failed. It may be the case that one method is always first one that failed. It may be the case that one method is always
expected to fail, and thus returning that method's specific code is expected to fail, and thus returning that method's specific code is
not information useful to the sending agent. not information useful to the sending agent.
The reverse IP DNS check is defined in Section 2.6.3 of [RFC7001]. The reverse IP DNS check is defined in Section 2.6.3 of [RFC7001].
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[RFC7001] Kucherawy, M., "Message Header Field for Indicating [RFC7001] Kucherawy, M., "Message Header Field for Indicating
Message Authentication Status", RFC 7001, September 2013. Message Authentication Status", RFC 7001, September 2013.
[RFC7208] Kitterman, S., "Sender Policy Framework (SPF) for [RFC7208] Kitterman, S., "Sender Policy Framework (SPF) for
Authorizing Use of Domains in Email, Version 1", RFC 7208, Authorizing Use of Domains in Email, Version 1", RFC 7208,
April 2014. April 2014.
Appendix A. Acknowledgments Appendix A. Acknowledgments
Claudio Allocchio, Ned Freed, Arnt Gulbrandsen, Scott Kitterman, Claudio Allocchio, Dave Crocker, Ned Freed, Arnt Gulbrandsen, Scott
Barry Leiba, Alexey Melnikov, and Hector Santos contributed to this Kitterman, Barry Leiba, Alexey Melnikov, and Hector Santos
work. contributed to this work.
Author's Address Author's Address
Murray S. Kucherawy Murray S. Kucherawy
270 Upland Drive 270 Upland Drive
San Francisco, CA 94127 San Francisco, CA 94127
USA USA
EMail: superuser@gmail.com EMail: superuser@gmail.com
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