NANOG List posts and DMARC

Michael Thomas mike at
Tue Aug 2 19:50:47 UTC 2022

On 8/2/22 12:30 PM, Jim Popovitch via NANOG wrote:
> On Tue, 2022-08-02 at 11:24 -0700, Michael Thomas via NANOG wrote:
>> On 8/2/22 11:18 AM, Chris Adams via NANOG wrote:
>>> Once upon a time, Chris Adams <cma at> said:
>>>> Once upon a time, Jared Mauch <jared at> said:
>>>>> Can someone flip the option in Mailman for DMARC please, it’s problematic as if one posts and does DMARC and has feedback on, our messages are  possibly rejected, and the feedback from a post is quite large.
>>>> The list is doing the DMARC handling (From rewrite) for senders with a
>>>> DMARC p=reject.
>>> Oh, or someone just changed the config per your request. :)  I have
>>> p=none but my From got rewritten on this message.
>> I think it's been doing this for ages. It was the first time I'd seen
>>   From rewriting in the wild iirc.
> It's been doing it for ages for p=reject, but not p=none (the latter
> being Jared's situation)
> There are toggles in MM2 to do DMARC address rewriting for p=none and
> p=quarantine in addition to p=reject.
I'm sort of surprised that an org would have p=reject when its users use 
outside mailing lists. Most mailing lists probably don't even have From 
rewriting or the mailing list operator is clueless about the problem. 
(think: non-technical mailing lists).


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