Network Working Group E. Allman
Request for Comments: 5617 Sendmail, Inc.
Category: Standards Track J. Fenton
Cisco Systems, Inc.
M. Delany
Yahoo! Inc.
J. Levine
Taughannock Networks
August 2009
DomainKeys Identified Mail (DKIM) Author Domain Signing Practices (ADSP)
Abstract
DomainKeys Identified Mail (DKIM) defines a domain-level
authentication framework for email to permit verification of the
source and contents of messages. This document specifies an adjunct
mechanism to aid in assessing messages that do not contain a DKIM
signature for the domain used in the author's address. It defines a
record that can advertise whether a domain signs its outgoing mail as
well as how other hosts can access that record.
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright Notice
Copyright (c) 2009 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 in effect on the date of
publication of this document (http://trustee.ietf.org/license-info).
Please review these documents carefully, as they describe your rights
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Allman, et al. Standards Track [Page 1]RFC 5617 ADSP August 2009Table of Contents
1. Introduction ....................................................3
2. Language and Terminology ........................................3
2.1. Terms Imported from the DKIM Signatures Specification ......3
2.2. Valid Signature ............................................4
2.3. Author Address .............................................4
2.4. Author Domain ..............................................4
2.5. Alleged Author .............................................4
2.6. Author Domain Signing Practices ............................4
2.7. Author Domain Signature ....................................4
3. Operation Overview ..............................................5
3.1. ADSP Applicability .........................................5
3.2. ADSP Usage .................................................6
3.3. ADSP Results ...............................................6
4. Detailed Description ............................................7
4.1. DNS Representation .........................................7
4.2. Publication of ADSP Records ................................7
4.2.1. Record Syntax .......................................7
4.3. ADSP Lookup Procedure ......................................9
5. IANA Considerations ............................................10
5.1. ADSP Specification Tag Registry ...........................10
5.2. ADSP Outbound Signing Practices Registry ..................11
5.3. Authentication-Results Method Registry Update .............11
5.4. Authentication-Results Result Registry Update .............11
6. Security Considerations ........................................13
6.1. ADSP Threat Model .........................................14
6.2. DNS Considerations ........................................14
6.3. DNS Wildcards .............................................15
6.4. Inappropriate Application of Author Domain Signatures .....15
7. References .....................................................16
7.1. Normative References ......................................16
7.2. Informative References ....................................16
Appendix A. Lookup Examples ......................................17
A.1. Domain and ADSP Exist .....................................17
A.2. Domain Exists, ADSP Does Not Exist ........................17
A.3. Domain Does Not Exist .....................................17
Appendix B. Usage Examples .......................................18
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