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Re: [dmarc-ietf] Doing a tree walk rather than PSL lookup

Joseph Brennan <brennan@columbia.edu> Tue, 24 November 2020 15:00 UTC

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In-Reply-To: <efa0117e-5b17-800d-820d-b5d2413c6075@tana.it>
From: Joseph Brennan <brennan@columbia.edu>
Date: Tue, 24 Nov 2020 10:00:16 -0500
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To: IETF DMARC WG <dmarc@ietf.org>
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Archived-At: <https://mailarchive.ietf.org/arch/msg/dmarc/CYFznscHJ6is8tGUBh_YFgK5VIM>
Subject: Re: [dmarc-ietf] Doing a tree walk rather than PSL lookup
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I will ask why the recipient system should look up anything but the dmarc
record for the specific domain in the Header From.

In some cases looking up related domains is useful, and in some cases it
can lead to disruption. We don't look up SPF records for related domains,
because they are deliberately different in many cases, e.g. one domain for
mail from end users, another for mail sent by a vendor, yet another for
another vendor. Why is dmarc different?


-- 
Joseph Brennan
Lead, Email and Systems Applications
Columbia University Information Technology

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