Re: [dmarc-ietf] Proposed text for p=reject and indirect mail flows

[Scott Kitterman <[e-mail]>]

Would you feel any better if the MUST NOT was followed by 'to preserve interoperability '?  That's implicitly there and I believe technically correct.  If you value other properties of the system higher than interoperability, then the advice may not apply, which is fine.

Scott K

On March 29, 2023 3:32:10 PM UTC, "Brotman, Alex" <Alex_Brotman=[e-mail]> wrote:
>I’m just not sure how we determine what is high-value.
>
>comcast.com: p=reject
>comcast.net: p=none
>xfinity.com: p=quarantine
>
>The top one is corporate, middle is consumer, bottom is consumer (but not actually used) & customer comms (sub-domains).  They’re all used in various ways for internal messaging.  Should I tell our corporate admins that they need to no longer publish p=reject?  They’re violating the RFC by doing so?  There are very few consumer-oriented messages that originate from comcast.com.  Are we doing it right?  It makes things a little harder when one of our employees wants to use a mailing list.  But that still feels like the right thing to do.
>
>If it’s not obvious, I’m having a hard time with “MUST NOT”, and dictating to domain owners what is in their best interests, regardless of our perceived value of their domain.
>
>--
>Alex Brotman
>Sr. Engineer, Anti-Abuse & Messaging Policy
>Comcast
>
>From: dmarc <[e-mail]> On Behalf Of Barry Leiba
>Sent: Wednesday, March 29, 2023 10:15 AM
>To: Todd Herr <todd.herr=[e-mail]>
>Cc: [e-mail]
>Subject: Re: [dmarc-ietf] Proposed text for p=reject and indirect mail flows
>
>I'm very much against text such as this, as I think it encourages deployments that are contrary to interoperability and to the intent of p=reject.
>
>I contend that p=reject (as with the similar construct in the older ADSP) was intended for high-value domains and transactional mail, and that it was never intended for use in domains where general users send general email.
>
>I stand by the MUST NOT that I proposed.
>
>Barry
>
>
>On Wed, Mar 29, 2023 at 10:33 PM Todd Herr <todd.herr=[e-mail]<mailto:[e-mail]>> wrote:
>On Tue, Mar 28, 2023 at 9:06 PM Pete Resnick <[e-mail]<mailto:[e-mail]>> wrote:
>
>If you agree that interoperability is increased, then I'd suggest that you actually do agree that the proposed text is appropriate.
>
>
>I don't know that I agree that interoperability is increased...
>
>I'm having trouble squaring proposed language that says "Domain owners MUST NOT publish p=reject because it breaks interoperability" with the following language from section 5.8:
>
>
>Mail Receivers **MAY** choose to accept email that fails the DMARC
>
>mechanism check even if the published Domain Owner Assessment Policy
>
>is "reject". In particular, because of the considerations discussed
>
>in [@!RFC7960], it is important that Mail Receivers **SHOULD NOT** reject
>
>messages solely because of a published policy of "reject", but that
>
>they apply other knowledge and analysis to avoid situations such as
>
>rejection of legitimate messages sent in ways that DMARC cannot
>describe, harm to the operation of mailing lists, and similar.
>
>It seems inconsistent to state with certainty that authorized mail will be rejected due to authentication breakage when there is no requirement that a reject policy be honored (and we have plenty of evidence that Mail Receivers are following the 'SHOULD NOT reject messages' guidance).
>
>Language that would be more consistent in guidance to the domain owners might look something like this:
>
>After careful analysis of the aggregate report data as described in section 5.5.5
>(Collect and Analyze Reports), Domain Owners **MAY** choose to change their
>policy from 'none' to 'quarantine' or 'reject'. If, in the Domain Owner's judgement,
>unauthorized and deceptive use of its domain name in the RFC5322.From field puts
>at risk the trust it has built with its recipients, then it is **RECOMMENDED** that
>the Domain Owner make use of the p and/or sp tags to set policy to 'quarantine' or
>'reject' for those streams most at risk of loss of trust.
>
>If going that route, probably want to consider expanding on 5.5.5, too; I need to think about it some more.
>
>--
>Todd Herr | Technical Director, Standards and Ecosystem
>e: [e-mail]<mailto:[e-mail]>
>m: 703.220.4153
>
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