Hm...
On Wed 23/Mar/2022 03:08:35 +0100 Douglas Foster wrote:
During my ruminations last night, I gained some clarity around that
question and wanted to highlight those conclusions. They simplify the
alignment search significantly:
- If the common substring is shorter than the Organizational Domain, then the
names are not aligned and the candidate domain can be ignored.
- Otherwise, if any candidate domain is a parent of (or equal to) the FROM
domain, then and we have alignment and DMARC PASS. The secondary tree walk is
not needed and no further evaluation is required.
- If several candidate names are child domains of the FROM address, then only
the shortest string needs to be evaluated with a secondary tree walk. If it is
aligned, further evaluation is not required. If it is not aligned because of
an organizational boundary, all other child domains are also excluded.
That and the deeper-than-5 optimization Doug posted on a separate message.
I know the document is already longish. However, collecting these observations
in an appendix may be helpful for developers, and maybe also for general
understanding of the intricacies involved in the tree walk, including proper
usage of the psd= flag.
Best
Ale
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