[Bug 1539384] Re: Non-blocking DMARC mitigations should also be done for p=none

Stephen Turnbull stephen at xemacs.org
Sun Dec 25 19:19:06 EST 2016

I believe the OP can get exactly the effect he wants by specifying a
DMARC policy record including "p=quarantine; pct=0". Mailman doesn't
(and arguably shouldn't) check the value of pct, let alone roll dice, on
p=quarantine or p=reject, so this policy will cause Mailman to mitigate
(if mitigation is available in that version of Mailman and requested by
the list admin).  On the other hand, pct=0 means no conforming recipient
implementation will actually quarantine any messages.  (Yes, pct=0 is
explicitly permitted by the RFC.)  The vast majority of mail is covered
by conforming implementations according to DMARC.org testing (but I
don't know that this corner case was tested -- someone with a test
domain can do that easily enough, and if someone does, please report
whether it worked and which providers were tested to mailman-
users at python.org).

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  Non-blocking DMARC mitigations should also be done for p=none

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