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Re: [dmarc-ietf] Thoughts on choosing N

Scott Kitterman <sklist@kitterman.com> Mon, 15 April 2024 23:09 UTC

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Date: Mon, 15 Apr 2024 23:09:00 +0000
From: Scott Kitterman <sklist@kitterman.com>
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Subject: Re: [dmarc-ietf] Thoughts on choosing N
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On April 15, 2024 4:34:40 PM UTC, John Levine <johnl@taugh.com> wrote:
>It appears that Alessandro Vesely  <vesely@tana.it> said:
>>8 is not needed and not justified.  A mail site using 8 labels would have 
>>troubles with the RFC 7489 version, which uses the PSL.  They'd have to ask for 
>>PSL upgrades, right?
>
>No, they would not. They might ask to have their pseudo-TLDs added to
>the PSL but there's a process for that and it is definitely not our
>problem.
>
>>Now, we can relax our ambition to be PSL-free and state N=max number of labels 
>>of public suffixes used by mail.  Or we could put N in an IANA registry that 
>>can be updated by expert review.  Such methods allow to have N low enough, yet 
>>upgradable and equal for all (compliant) implementations.
>
>That is a great deal of complication for no benefit whatever.
>
>I'm with Scott, pick a number, 5, 8, whatever, and be done with it.
>
Modulo we do need to explain why 8. Related, I think we also need to explain why the reporting address thing is important for DMARCbis since having an intermediate level record isn't currently supported by DMARC.

Scott K

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