Are we *again* questioning the tree walk, which is, recall, a settled issue?

Barry

On Sun, Jun 11, 2023 at 7:53 AM Douglas Foster
<[email protected]> wrote:
>
> Given that the PSL is subject to errors, it is reasonable to warn senders that
>
> "Because of the risk of PSL errors, some evaluators MAY NOT accept some or 
> all forms of relaxed alignment as acceptable authentication."
>
> Technically, this is just stating the obvious, since evaluators MAY do 
> whatever they want.  Then the inference from that warning is:
>
> "Senders SHOULD avoid configurations that depend on the PSL for 
> authentication.   This is accomplished by publishing a DMARC policy on both 
> the organizational domain and any mail-sending subdomains, and by using 
> strict alignment on those policies."
>
> But strict alignment will be burdensome for some configurations, so an 
> intermediate solution would be:
>
> - define an optional "organizational domain" token for DMARC policies.   If 
> present, it must be equal to or a parent of the current domain.
> - If the token is provided AND matches the PSL, then the organizational 
> domain is considered safe for relaxed alignment.   If the token is provided 
> but does not match the PSL, then the longer of the two domain names will be 
> used for relaxed alignment.
>
> By using same-domain DMARC policy, senders permit improved efficiency for 
> evaluators while protecting both senders and evaluators from PSL errors.
>
> Doug Foster
>
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