[Mailman-Users] cause of bounces

[Mark Sapiro]

On 10/17/2017 03:28 PM, Grant Taylor via Mailman-Users wrote:
> On 10/17/2017 04:15 PM, Lindsay Haisley wrote:
>> Just as an aside here, my understanding is that validation of an email
>> by DMARC requires ONE of two things: EITHER the DKIM signature in the
>> email must validate, OR the domain of the From body header must
>> resolve to the IP address of the Sender system (list server or mail
>> reflector).  Is this correct? Where's a reference on this?
> 
> That is a per domain setting left up to the DMARC publisher.


Not quite.


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

No. The standard says DMARC passes if either SPF or DKIM passes with an
aligned domain. The only thing the DMARC publisher controls for one or
the other or both is whether alignment is strict or relaxed.

See my post that I was still typing when this was sent
<https://mail.python.org/pipermail/mailman-users/2017-October/082621.html>.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan