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In message <[email protected]
il.com>, Seth Blank <[email protected]> writes

>    As an individual, I have seen evidence that ARC is strongly adopted 
>    by the major mailbox providers (Google and Microsoft in particular) 

it is true that they add ARC header fields

>    who find it valuable. 

they must comment for themselves ... at $DAYJOB$ we have found that the
way in which Google adds ARC header fields makes it counter-productive
to trust them, so they have been removed from our "trusted" list (they
add a second set of ARC header fields despite the message having been in
the hands of bad people, who have altered it to make the message
malicious, and hence you will accept their assertions as to the
provenance of the email at your (considerable) peril).

>    Their mainstream support articles that talk
>    about authenticating your mail all have sections that tell senders 
>    who modify messages to ARC Seal those messages, so it’s not niche 
>    guidance either.

I think you will find that that advice has now disappeared (and/or has
been significantly watered down)

>    I hope these MBPs can share data with this list on usage and impact 
>    to inform the IETF’s decision making here.

experience from $DAYJOB$ is that implementing ARC checking does not
improve email security -- despite considerable work to tweak our
implementation to try and detect malicious flows.

> I think obsoleting a 
>    standard that’s clearly in use and valuable, just because we don’t 
>    have enough data on this list yet, is a mistake, and we should at 
>    least endeavor to get the data first.

$DAYJOB$ has a lot of data ... and we have concluded that is not
valuable. We have contributed some text to the IETF-draft to explain the
nature of the failures we have seen.

>    My belief is that this working group should not recharter and 
>    should wind down as intended. When there is a technology that 
>    supersedes ARC (like DKIM2), that document should be what moves the 
>    ARC bit to obsolete or historic, not us.

I believe that this draft should progress. I don't especially care in
which working group that happens, but here is as simple as anywhere and
since other work has concluded people who do not wish to read about ARC
can simply unsubscribe.

We should not give anyone the impression that spending any new
engineering cycles on ARC is worthwhile.

- -- 
richard                       writing to inform and not as company policy

"Assembly of Japanese bicycle require great peace of mind" quoted in ZAMM

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