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Re: [dmarc-ietf] third party authorization, not, was non-mailing list

John R Levine <johnl@taugh.com> Tue, 25 August 2020 18:13 UTC

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Date: Tue, 25 Aug 2020 14:13:46 -0400
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From: John R Levine <johnl@taugh.com>
To: Dotzero <dotzero@gmail.com>
Cc: IETF DMARC WG <dmarc@ietf.org>
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Subject: Re: [dmarc-ietf] third party authorization, not, was non-mailing list
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On Tue, 25 Aug 2020, Dotzero wrote:
>>> I would expect there to be multiple potential approaches to identifying
>>> acceptable intermediaries.
>>
>> The harder part is to decide which intermediary gets to re-sign which
>> message at the time you apply the weak signature.
>
> It would have be the domain in the "To" field.  It wouldn't work with
> random unknown intermediaries. It would address the MLM issue as long as
> the MLM domain is the same as the "To" domain when the message was
> originally sent. It could also presumably work for vanity domains if they
> DKIM sign. It wouldn't work for forwards on the receiver side that the
> sender is unaware of.

If the list is somelist@lists.foo.org, does the signature have to be 
d=lists.foo.org?  How about d=foo.org?

On the flip side, do you put a weak signature on all of your outgoing 
mail, which seems like a bad idea, or just mail that you expect to go 
through list modification?  In the latter case, how do you tell?  These 
are the scaling problems that I fear make this unworkable.

Regards,
John Levine, johnl@taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly

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