It appears that Scott Kitterman  <[email protected]> said:
>My impression is that the group is generally okay with PSD=y.  I prefer it 
>over your suggestion.  My strongest preference is that we pick something, 
>stick with it, and move on.

I think I see where Ale's confusion is coming from. If we switch to a
tree walk, we will have an algorithm rather than a heuristic, so
anyone looking at the same domains and the same set of DMARC records
will get the same result. It also occurs to me that in the absence of
a PSL-like thing, the idea of an organizational domain is no longer
useful.

There's two questions to answer: what is the policy for a domain, and are two 
domains in relaxed alignment.

The answer to the first one is straightforward: start at the domain, walk up 
the tree, and the first DMARC record
you find is the policy record.  If you don't find one, there's no policy.

The answer to the second has two cases:

If one domain is a subdomain of the other, and there is no policy record (or 
maybe no PSD policy record) between
them, they're in relaxed alignment.

If they are cousin domains, walk up the tree from each until you find a policy 
record.  If you find the same policy
record and it's not a PSD and it allows relaxed alignment, they're in relaxed 
alignment.  If you find different
records, or only one record, or no records, they aren't.

As a special case, a domain with a PSD record is never aligned with anything 
but itself.
(I realize .bank will never send mail, but us.com might.)

The cousin domain rule doesn't exactly reproduce what the PSL is intended to 
do, but I think it covers
the useful cases and is unlikely to allow accidental cousin alignment which 
Mike keeps reminding us about.

Suggestions and tweaks (with an explanation of what problem they fix) welcome.

R's,
John


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