Early Review of draft-ietf-spfbis-4408bis-14
review-ietf-spfbis-4408bis-14-secdir-early-hallam-baker-2013-05-02-00

I have reviewed this document as part of the security directorate's

ongoing effort to review all IETF documents being processed by the

IESG.  These comments were written primarily for the benefit of the

security area directors.  Document editors and WG chairs should treat

these comments just like any other last call comments.

The document is clear and describes the SPF mechanism effectively. The only
quibble that I could find is that repeated mentions are made of limiting the
number of 'DNS queries' without specifying whether these are individual queries
or recursive. The count will come out rather differently if looking up TXT/

x.example.com

 counts as one lookup or three. I think it is reasonably clear that this is one
 but could not find an explicit statement to that effect.

On the security side, the document addresses all the mail issues that I can
remember at this point and rather more besides.

I think we have reached the point of diminishing returns.

The document provides a clear enough warning to people configuring SPF records
as to the consequences of getting it wrong which is the main concern. The
filtering services will know their business well enough to minimize false
positives.

Hopefully the email infrastructure will evolve over time towards concentrating
on the more policy friendly approaches and it will be possible to simplify the
mechanism at a future date.

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