Re: [dmarc-ietf] Some Proposed Language for a New pct Tag Defintion

Todd Herr <> Tue, 03 August 2021 12:08 UTC

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From: Todd Herr <>
Date: Tue, 3 Aug 2021 08:08:18 -0400
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To: John Levine <>
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Subject: Re: [dmarc-ietf] Some Proposed Language for a New pct Tag Defintion
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On Mon, Aug 2, 2021 at 10:10 PM John Levine <> wrote:

> It appears that Todd Herr  <> said:
> >> I like simple, but I also like the idea of a separate section that
> >discusses the history of the pct tag and why the old values won't work any
> >longer.
> OK except:
> >   remains the default, and "0".  The value of "0" took on unintended
> >   significance during the experimental stage as a value used by some
> >   intermediaries and mailbox providers as an indicator to either
> >   deviate from standard handling of the message and/or to alter the
> >   substance of reports generated, ...
> Alter the reports?  Huh?  I was under the impression that the policy didn't
> affect the reports, much less the pct.
My apologies...

My memory of the effect of the policy "p=quarantine; pct=0" vis-a-vis how
Google handles a domain's mail was faulty. I remember when working to
implement DMARC at $JOB[-1] for our corporate domain, I was seeing data in
the agg reports from Google when we were at p=none that led me to ask "WTF
are those hosts?" and digging around the various corners of the internet
unearthed the unknown at the time to me fix of "Yeah, you gotta be at
p=quarantine; pct=0" to get reports from Google that make sense.

There are several years old threads on mailop that speak to this topic,
with outsiders asserting that what is in fact happening is Google Groups is
rewriting the From when it's p=quarantine; pct=0, and Brandon Long from
Google in the thread doesn't challenge that assertion, so I'll remove
reference to the reporting alteration.


*Todd Herr* | Technical Director, Standards and Ecosystem
*m:* 703.220.4153

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