Subject: Protocol Action: 'Sender Policy Framework (SPF) for Authorizing Use of Domains in Email, Version 1' to Proposed Standard (draft-ietf-spfbis-4408bis-21.txt)

From: The IESG <[email-masked]>
Date: Fri, 17 Jan 2014 11:48:05 -0800

The IESG has approved the following document:
- 'Sender Policy Framework (SPF) for Authorizing Use of Domains in Email,
   Version 1'
  (draft-ietf-spfbis-4408bis-21.txt) as Proposed Standard

This document is the product of the SPF Update Working Group.

The IESG contact persons are Pete Resnick and Barry Leiba.

A URL of this Internet Draft is:
http://datatracker.ietf.org/doc/draft-ietf-spfbis-4408bis/

Technical Summary

  draft-ietf-spfbis-4408bis describes version 1 of the Sender Policy
  Framework (SPF) protocol, whereby Administrative Management Domains
  can explicitly authorize the hosts that are allowed to use its domain
  names, and a receiving host can check such authorization.

  The working group was chartered to produce a document as a Proposed
  Standard defining the SPF protocol based upon RFC 4408 (Experimental).

Working Group Summary

   This document is a product of the SPFBIS working group, and has been
    through a large number of revisions including a complete reorganization
    of the document.  The working group dealt with a number of controversial
    topics.  The following outlines how those were resolved:

    There was an intermediate conclusion about the topic of whether the SPF
    protocol should use the SPF RRTYPE or the TXT resource record.  It was
    followed by an objection.  After discussion of the topic at the IETF 83
    SPFBIS WG session the conclusion reached was that the decision would be
    not to publish RRTYPE 99 and and not to query RRTYPE 99.  The WG
    consensus about the RRTYPE can be described as particularly rough.  The
    topic of obsoleting the SPF RRTYPE generated a lot of controversy near
    the end of the WGLC.  There were a very high number of messages about
    the topic on the SPFBIS mailing list and the DNSEXT mailing list as some
    DNSEXT WG participants were not aware of RFC 6686.
  
    The topic of whether the SPF protocol has to reject mail or not when
    the result of the evaluation is "Fail" was actively discussed.  It
    was determined that it was a matter of local policy.
    
    There was discussion about standardizing the "best guess" heuristics to 
    guess possible SPF policies for domains that do not publish an SPF record.
    The WG consensus was not to standardize the heuristics.

    The topic of mail forwarding and mailing lists in respect to the SPF
    protocol was not too controversial in comparison with the other
    controversies.  The WG consensus was to have the document discuss about
    the topic in a non-normative manner.

    There was some controversy about whether the use of macros was a
    security risk and whether to deprecate the PTR feature.  There was a
    formal appeal of the SPFBIS WG chair' interpretation of the charter,
    specifically regarding the removal of "unused" features.  The two
    features in particular which drove the appeal were the PTR feature
    and the local-part macro feature.  These features were not removed
    from the document given that the appeal was denied by the Responsible
    Area Director.

    There was significant discussion about whether to use the
    "Received-SPF:" header field or whether to use the
    "Authentication-Results" header field to record the results of a SPF
    evaluation.  The working group decided to add both header fields in
    the document as they are in common use.

    There was a suggestion to reorganize the document.  It was argued that
    the document had become somewhat bloated with documentation of nuance
    and other text that has nothing to do with defining a protocol and
    enabling interoperability.  This led to a stalemate.  Based on the
    discussion during the SFPBIS WG session at IETF 85 the WG decided to
    proceed with a reorganization of the document while ensuring that the
    reorganization did  not create any text changes apart from moving text
    around.

   There is rough consensus within the SPFBIS WG to publish the document.

   Some WG participants have mentioned that they may express extreme
   discontent about the decision to obsolete the SPF RRTYPE during
   the Last Call.

Document Quality

   There are multiple existing implementations of the SPF protocol.  The
   document was reviewed by the SPFBIS working group.  Dave Crocker,
   Stuart Gathman, Murray Kucherawy, John Levine,  Hector Santos,
   Andrew Sullivan, Arthur Thisell, and Alessandro Vesely reviewed the
   document.  Simon Perreault helped to clarify the meaning of IPv4 mapped
   IPv6 addresses.  Murray Kucherawy deserves a special mention for his
   contributions.

   The document was reviewed by Cyrus Daboo on behalf of the Applications
   Area Directorate.   Meral Shirazipour reviewed the document for Gen-ART
   and Phillip Hallam-Baker performed the Security Directorate review.

Personnel

   S. Moonesamy is the Document Shepherd for this document. Pete Resnick
   is the Responsible Area Director.

RFC Editor Note

   Please note that the charter of this WG was to produce a document that
   minimizes changes from RFC 4408. When copy editing is done, please
   compare to RFC 4408 and try to minimize copy edits that might
   accidentally change the meaning from there.

   Also note that I have added citations for each of the "Works in
   Progress". I don't know if the RFC Editor needs those; strike them
   if they aren't needed.

   Please change the following, as agreed by the WG:

   Section 4.6:
   OLD
   The check_host() function parses and interprets the SPF record to
   find a result for the current test.  If there are any syntax errors
   anywhere in the record, check_host() returns immediately with the
   result "permerror", without further interpretation.
   END

   NEW
   The check_host() function parses and interprets the SPF record to
   find a result for the current test.  The syntax of the record is
   validated first, and if there are any syntax errors anywhere in the
   record, check_host() returns immediately with the result "permerror",
   without further interpretation or evaluation.
   END

   Section 5.5:
   OLD
   Pseudocode:

   sending-domain_names := ptr_lookup(sending-host_IP);
   if more than 10 sending-domain_names are found, use at most 10.
   for each name in (sending-domain_names) {
     IP_addresses := a_lookup(name);
     if the sending-domain_IP is one of the IP_addresses {
       validated-sending-domain_names += name;
     }
   }

   for each name in (validated-sending-domain_names) {
     if name ends in <target-name>, return match.
     if name is <target-name>, return match.
   }
   return no-match.
   END

   NEW
   END
   (That is, delete the above bit.)

   Section 15.2:
   OLD
   [DMP]      Fecyk, G., "Designated Mailers Protocol".

              Work In Progress

   [Green]    Green, D., "Domain-Authorized SMTP Mail", 2002.
   NEW
   [BATV]     Levine, J., "Bounce Address Tag Validation (BATV)", 2008.
              Work In Progress (draft-levine-smtp-batv-01.txt)

   [DMP]      Fecyk, G., "Designated Mailers Protocol".
              Work In Progress (draft-fecyk-dmp-02)

   [Green]    Green, D., "Domain-Authorized SMTP Mail", 2002.
              Work In Progress (http://www.mhonarc.org/archive/html/ietf-asrg/2003-03/msg01525.html)
   END

   OLD
   [RMX]      Danisch, H., "The RMX DNS RR Type for light weight sender
              authentication".

              Work In Progress
   NEW
   [RMX]      Danisch, H., "The RMX DNS RR Type for light weight sender
              authentication".
              Work In Progress (draft-danisch-dns-rr-smtp)
   END

   Appendix D.1:
   OLD

      Note that due to the 63-character limit for domain labels, this
      approach only works reliably if the local-part signature scheme is
      guaranteed either to only produce local-parts with a maximum of 63
      characters or to gracefully handle truncated local-parts.

   NEW

      Note that due to the 63-character limit for domain labels, this
      approach only works reliably if the local-part signature scheme is
      guaranteed either to only produce local-parts with a maximum of 63
      characters or to gracefully handle truncated local-parts.  The
      method used to secure the localpart is a local implementation
      issue, it need not be standard.  An example of one way to do it
      can be found in [BATV].