Authentication-Results Registration for Vouch by Reference Results
RFC 6212

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Internet Engineering Task Force (IETF)                      M. Kucherawy
Request for Comments: 6212                               Cloudmark, Inc.
Category: Standards Track                                     April 2011
ISSN: 2070-1721

   Authentication-Results Registration for Vouch by Reference Results

Abstract

   This memo updates the registry of properties in Authentication-
   Results: message header fields to allow relaying of the results of a
   Vouch By Reference query.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in 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/rfc6212.

Copyright Notice

   Copyright (c) 2011 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                    Standards Track                    [Page 1]
RFC 6212              Auth-Results VBR Registration           April 2011

Table of Contents

   1. Introduction ....................................................2
   2. Keywords ........................................................2
   3. Discussion ......................................................2
   4. Definition ......................................................3
   5. IANA Considerations .............................................4
   6. Security Considerations .........................................5
   7. References ......................................................5
      7.1. Normative References .......................................5
      7.2. Informative References .....................................5
   Appendix A.  Authentication-Results Examples .......................6
     A.1.  VBR Results ................................................6
   Appendix B.  Acknowledgements ......................................7

1.  Introduction

   [AUTHRES] defined a new header field for electronic mail messages
   that presents the results of a message authentication effort in a
   machine-readable format.  In the interim, a proposal for rudimentary
   domain-level reputation assessment, called Vouch By Reference, [VBR]
   was published and is now beginning to see popular use.

   This memo thus registers an additional reporting property allowing a
   VBR result to be relayed as an annotation in a message header.

2.  Keywords

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [KEYWORDS].

3.  Discussion

   Vouch By Reference [VBR] introduced a mechanism by which a message
   receiver can query a "vouching" service to determine whether or not a
   trusted third party is willing to state that mail from a particular
   source can be considered legitimate.  When this assessment is done at
   an inbound border mail gateway, it would be useful to relay the
   result of that assessment to internal mail entities such as filters
   or user agents.

   Reactions to the information contained in an Authentication-Results
   header field that contains VBR (or any) results are not specified
   here, as they are entirely a matter of local policy at the receiver.

Kucherawy                    Standards Track                    [Page 2]
RFC 6212              Auth-Results VBR Registration           April 2011

4.  Definition

   This memo adds to the "Email Authentication Methods" registry,
   created by IANA upon publication of [AUTHRES], the following:

   o  The method "vbr"; and

   o  Associated with that method, the properties (reporting items)
      "header.md" and "header.mv".

   If "header.md" is present, its value MUST be the DNS domain name
   about which a VBR query was made.  If "header.mv" is present, its
   value MUST be the DNS domain name that was queried as the potential
   voucher for the "header.md" domain.

   If the VBR query was made based on the content of a "VBR-Info" header
   field present on an incoming message, "header.md" is typically taken