[Mailman-Users] cause of bounces

[Lindsay Haisley]

On Tue, 2017-10-17 at 16:28 -0600, Grant Taylor via Mailman-Users
wrote:
> That is a per domain setting left up to the DMARC publisher.

The DMARC publisher is not the system refusing delivery. The publisher
advertises a policy. The receiving system honors it, or not.

> At least my understanding is that you can specify any of the
> following=20
> conditions to cause DMARC to pass / fail.
> 
> 1) /Only/ SPF
> 2) /Only/ DKIM
> 3) SPF /or/ DKIM
> 4) SPF /and/ DKIM

Any system which REQUIRES DKIM validation to pass is out of compliance
with RFCs, as I understand it. A DKIM signature which doesn't validate
MUST be treated the same as no DKIM signature at all.

And I don't believe we're dealing with SPF here, just alignment between
the domain of an email's author (From) and the IP address of the system
communicating SMTP server from which the recipient's SMTP server
received the mail. Correct me if I'm wrong on this, but I don't believe
a SPF record in DNS is required.

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Lindsay Haisley       | "The first casualty when
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