Re: [dmarc-ietf] DMARC PSD and non-existent subdomains

Seth Blank <seth@sethblank.com> Thu, 30 May 2019 23:43 UTC

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From: Seth Blank <seth@sethblank.com>
Date: Thu, 30 May 2019 16:43:28 -0700
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To: Richard C <Richard.C=40ncsc.gov.uk@dmarc.ietf.org>
Cc: "dmarc@ietf.org" <dmarc@ietf.org>
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Subject: Re: [dmarc-ietf] DMARC PSD and non-existent subdomains
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On Thu, May 30, 2019 at 9:06 AM Richard C <Richard.C=
40ncsc.gov.uk@dmarc.ietf.org> wrote:

> What would be the best way to incorporate this requirement?
>

The simplest possible way to address this use case is just to make sure
those existing but currently non-compliant domains just have a bare p=none
record. Then they'll never fall back to the gov.uk record. There's no risk
to inadvertently breaking mail here.

It it remotely realistic for you to offer this guidance? If you're already
saying that p=reject is required, how painful is it to advertise that any
domain without a DMARC record will get p=reject by default unless it
explicitly puts p=none in?

Seth