DNSWL Email Authentication Method Extension
draft-vesely-authmethod-dnswl-00

The information below is for an old version of the document
Document Type Active Internet-Draft (individual)
Last updated 2013-07-15
Stream (None)
Intended RFC status (None)
Formats plain text pdf html bibtex
Stream Stream state (No stream defined)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date
Responsible AD (None)
Send notices to (None)
IETF                                                           A. Vesely
Internet-Draft                                             July 15, 2013
Intended status: Informational
Expires: January 16, 2014

              DNSWL Email Authentication Method Extension
                    draft-vesely-authmethod-dnswl-00

Abstract

   This document describes a method that can be registered within the
   Email Authentication Methods IANA registry created by RFC 5451.  The
   method consists in looking up a DNS whitelist.

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 January 16, 2014.

Copyright Notice

   Copyright (c) 2013 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.

Vesely                  Expires January 16, 2014                [Page 1]
Internet-Draft      DNSWL email-auth-method extension          July 2013

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Method Results  . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Implementation Status . . . . . . . . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     6.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     6.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Appendix A.  Example  . . . . . . . . . . . . . . . . . . . . . . . 7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 7

Vesely                  Expires January 16, 2014                [Page 2]
Internet-Draft      DNSWL email-auth-method extension          July 2013

1.  Introduction

   One of the many checks that mail servers carry out is to query DNS
   whitelists (DNSWL, [RFC5782]).  The semantics of DNSWL is similar to
   that of Vouch By Reference (VBR, [RFC5518]); that is, an external
   organization, trusted by the receiving mail transfer agent (MTA),
   vouches for the sender.

   Differently from VBR, the lookup is based on the IP address.  That
   allows it to occur very early in an SMTP transaction, and thus it can
   be used to counterweight policies that typically occur at those early
   stages too, such as the Sender Policy Framework (SPF, [RFC4408]).
   Nevertheless, the result of a DNSWL lookup is likely used at later
   stages as well; for example, a delivery agent can use it to estimate
   the spamminess of an email message.  Reusing the previously obtained
   result is more consistent than issuing multiple queries, and saves
   resources.

2.  Method Results

   In this document, the acronym DNSWL is used both to refer to a
   generic organization that publishes a whitelist, and to indicate the
   use of such service, that is the method.  The organization defines
   the DNS zone and the record type(s) to be queried, as well as the
   meaning of the listings and the procedures to maintain them.

   Unlike other methods, such as dkim or spf, there is little or no work
   to be carried out by the receiving MTA on the values retrieved from
   the DNS query.  As explained in Section 2.3 of [RFC5782], DNSWLs
   encode taxonomical details about the mail sender as bit masks of type
   A records.  The receiving MTA just needs to work out whether the data
   returned is at all applicable.  In that case, it uses that data as an
   outsourced extension of its local policy.  Thus, in a broad sense,
   the result of the method is the content returned by the query:

   dns.zone:   The name of the DNSWL, which defines the meaning of the
               result.  If the MTA uses a private mirror, this can be
Show full document text