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Re: [dmarc-ietf] non-mailing list use case for differing header domains

Laura Atkins <laura@wordtothewise.com> Tue, 28 July 2020 15:22 UTC

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From: Laura Atkins <laura@wordtothewise.com>
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Date: Tue, 28 Jul 2020 16:22:41 +0100
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Subject: Re: [dmarc-ietf] non-mailing list use case for differing header domains
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> On 28 Jul 2020, at 16:14, Alessandro Vesely <vesely@tana.it> wrote:
> 
> On Tue 28/Jul/2020 11:07:19 +0200 Laura Atkins wrote:
>>> On 28 Jul 2020, at 08:36, Alessandro Vesely <vesely@tana.it wrote:
>>> On Tue 28/Jul/2020 08:54:02 +0200 Autumn Tyr-Salvia wrote:
> 
>>>> # The resulting message uses executive@secondbrand.com in the friendly
>>>> From: field, but firstbrand.com  in the SMTP MAIL FROM domain, so the headers are no longer aligned for SPF. >>> #
>>> 
>>> Heck, can't they DKIM sign?
>> This really misses Autumn’s point. [...]
>> Autumn has presented a very real world scenario that demonstrates the
>> overall complexity of mail management operationally. Your solution “sign
>> with DKIM” has significant barriers to adoption. For instance, assume that
>> there is code installed on the mailserver that will grab the 5322.from
>> address and sign with the appropriate DKIM key. How many domains are
>> involved? How many different mailservers? How long will this solution take
>> to deploy? Banks do not move quickly and, for the obvious reasons, any
>> changes to security require multiple reviews and assurances that the
>> implications are understood.
> 
> 
> If the bank delegates a subdomain to each trusted subsidiary, each subsidiary could manage their keys on their local DNS and email servers.  If the bank can afford "relaxed" DKIM alignment, they can sign with d=local-branch.bank.example and From: transactions@bank.example.  What's the risk of doing so?

That does not address the problem Autumn brought up at all. 

laura 

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