Attached it is a spreadsheet with the problems from my data set.  If it is
dropped during the forwarding process, let me know and I will re-post it in
the body of the message.

The WG needs to prove that "The Tree Walk will cause no significant
disruption".    We should have understood that trying to prove a negative
is a very difficult undertaking.   Only one counterexample is needed to
disprove the assumption, and there is a near-infinite number of
counterexamples to be considered.   In this case, we embraced one favorable
report, without obtaining additional data, and without even asking whether
the mail stream used for testing is a plausible proxy for the general
Internet.

We do not need to speculate about "what the domain owner expected".   We
can reliably assume that the domain owner expected his message to be
evaluated by RFC 7489 rules using a correct PSL.   Did the Tree Walk
actually expose any PSL errors?  If not, then the RFC 7489+PSL result is
what was intended.

One could postulate this approach to finding and fixing problems in the PSL:
1) Evaluate incoming messages using both PSL and Tree Walk.
2) When the two techniques produce different results, study the message,
and consult other resources, to determine whether the PSL is correct or
not.   If the conclusion is a PSL error, make the PSL correction and note
the entry as verified.   If the Tree Walk result is in error, document that
result as well.
3) Repeat for each new discrepancy between the two methods.

My suspicion is that PSL errors will be very difficult to find by this
method, because the PSL will be correct in the overwhelming majority of
cases.   When the payback is infrequent, most evaluators will conclude that
the labor investment is not sufficient to the benefits gained.

I am not opposed to deprecating the PSL, just opposed to deprecating it
with a one-sided redesign of the protocol, using rosy assumptions.   I do
not want to create a clone of the mailing list problem.

Doug


On Sat, Oct 7, 2023 at 3:46 PM John Levine <[email protected]> wrote:

> It appears that Richard Clayton  <[email protected]> said:
> >I do wonder if this is the PSL raising its ugly head again. A remarkable
> >number of the people who have added entries have not understood how they
> >now need to publish rather more DNS records than previously ...
>
> Definitely. In the few cases we've found where a tree walk would
> provide a different result to the PSL, it is not clear which one the
> domain owner expected.
>
> R's,
> John
>
> _______________________________________________
> dmarc mailing list
> [email protected]
> https://www.ietf.org/mailman/listinfo/dmarc
>

Attachment: Tree Walk Error Details.xlsx
Description: MS-Excel 2007 spreadsheet

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