Issue 182 has been created for this thread -
https://github.com/ietf-wg-dmarc/draft-ietf-dmarc-dmarcbis/issues/182

On Thu, Feb 6, 2025 at 4:56 PM John R. Levine <[email protected]> wrote:

> > 296        Domain Owners can use these reports, especially the aggregate
> > 297        reports, not only to identify sources of mail attempting to
> > 298        fraudulently use their domain, but also (and perhaps more
> > 299        importantly) to flag and fix gaps in their own authentication
> > 300        practices.  However, as with honoring the Domain Owner's
> stated mail
> > ```
> > How common is it to receive information in these reports that is
> impossible to
> > fix? In other words, are these reports generating alert fatigue more
> often than
> > they are helping identify real threats? There is also the question of the
> > cost(cpu/memory/traffic/sustainability) of sending the reports.
>
> Fairly common, but DMARC reports are all sent and processed automatically.
> My tiny system has received over 600,000 reports over the years and the
> load has been negligible.  There are many services that will receive and
> process your reports for you if you don't want to do it yourself.
>
> > 816        Author Domain.  Neither approach is recommended, however.
> > ```
> > I assume:
> >
> > It is RECOMMENDED to enable both DKIM and SPF.
>
> Yes.
>
> > ### MUST NOT change p=none
> > ```
> > 1514       Identifiers being unaligned or missing entirely.  For such
> legitimate
> > 1515       uses, these shortcomings MUST be addressed prior to any
> attempt by
> > 1516       the Domain Owner to publish a Domain Owner Assessment Policy
> > 1517       (#domain-owner-policy) of Enforcement (#enforcement) for the
> Author
> > 1518       Domain.
> > ```
> >
> > How does this MUST achieve interoperability?
>
> If you publish p=none, people will accept your mail even if it's
> unaligned.  If you publish anything else they will reject it.  Cue long
> rant about mailing lists.
>
> > 1712       Per-message failure reports can be a useful source of
> information for
> > 1713       a Domain Owner, either for debugging deployments or in
> analyzing
> > 1714       attacks, and so Mail Receivers MAY choose to send them.
> Experience
> > 1715       has shown, however, that Mail Receivers rightly concerned
> about
> > 1716       protecting user privacy have either chosen to heavily redact
> the
> > 1717       information in such reports (which can hinder their
> usefulness) or
> > 1718       not send them at all.  See [I-D.ietf-dmarc-failure-reporting]
> for
> > 1719       further information.
> > ```
> >
> > This MAY reads to me as a SHOULD NOT, given the privacy risk can the
> guidance
> > be strengthened?
>
> it really depends on the system.  In practica hardly anyone sends faiure
> reports so it's not worth a lot of effort to tweak.
>
> > 1735       Mail Receivers MAY choose to accept email that fails the DMARC
> > 1736       validation check even if the published Domain Owner
> Assessment Policy
> > 1737       is "reject".  In particular, because of the considerations
> discussed
> > 1738       in [RFC7960] and in Section 7.4 of this document, it is
> important
> > 1739       that Mail Receivers SHOULD NOT reject messages solely because
> of a
> > 1740       published policy of "reject", but that they apply other
> knowledge and
> > 1741       analysis to avoid situations such as rejection of legitimate
> messages
> > 1742       sent in ways that DMARC cannot describe, harm to the
> operation of
> > 1743       mailing lists, and similar.
> > ```
> > The guidance here regarding reject feels like a weak point in the
> document.
> > In context, this reads as "reject" is NOT RECOMMENDED, and if present
> MAY be
> > ignored. It is RECOMMENDED to ignore it, when "other knowledge" enables
> > legitimate messages to be distinguished?
>
> That means mailing lists.
>
> > ```
> > 1857       If a Mail Receiver elects to defer delivery due to the
> inability to
> > 1858       retrieve or apply DMARC policy, this is best done with a 4xy
> SMTP
> > 1859       reply code.
> > ```
> > Should this guidance be normative?
>
> Never seen it heppen in practice.
>
> > 2399    11.7.  Secure Protocols
> >
> > 2401       This document encourages the use of secure transport
> mechanisms to
> > 2402       prevent the loss of private data to third parties that may be
> able to
> > 2403       monitor such transmissions.  Unencrypted mechanisms should be
> > 2404       avoided.
> >
> > 2406       In particular, a message that was originally encrypted or
> otherwise
> > 2407       secured might appear in a report that is not sent securely,
> which
> > 2408       could reveal private information.
> > ```
> > Is it possible to strengthen the guidance here (MUST / SHOULD)?
>
> Honestly, I would delete this entire section since so few people send
> failure reports.  I think it is entirely hypothetical.
>
> Regards,
> John Levine, [email protected], Primary Perpetrator of "The Internet for
> Dummies",
> Please consider the environment before reading this e-mail. https://jl.ly
>


-- 
Todd Herr
Some Guy in VA LLC
[email protected]
703-220-4153
Book Time With Me: https://calendar.app.google/tGDuDzbThBdTp3Wx8
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