Subject: Re: [dmarc-ietf] Tree walk is not a heuristic, was screwed up

From: Elizabeth Zwicky <[email-masked]>
Date: Fri, 11 Feb 2022 11:49:07 -0800

> On Jan 25, 2022, at 10:35 AM, John R Levine <[email-masked]> wrote:
> 
> Do we have any stats on how often real mail depends on sibling alignment? If nobody actually uses it, the spec would be simpler if we could take it out.

Stats are tricky, but here are some senders using sibling alignment like
From domain: samedaycity.FedEx.com
DKIM domain: freight.FedEx.com
SPF domain: nds.FedEx.com

Most of these don’t do it for all mail, but account and billing related mail or customer support mail are particularly likely to use it
FedEx, obviously
Uber
Intuit
NextDoor outside the US
Taco Bell
McGill university
Lots of healthcare billing using the Cedar platform
Atlassian
Alignable.com which tickles my sense of irony
Cmdlr.com which sends mail for a variety of car dealerships 

These are cherry-picked from a few minutes of incoming mail. So in practice, turning it off would cause significant disruption. 

Elizabeth 

> 
> Regards,
> John Levine, [email-masked], Taughannock Networks, Trumansburg NY
> Please consider the environment before reading this e-mail. https://jl.ly
> 
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