lists and DMARC and ARC, was Incoming SMTP in the year 2017 and absence of DKIM

John Levine johnl at
Wed Nov 29 21:11:18 UTC 2017

In article <1d458e76-ab61-db28-79cb-6aabcab4ff3b at> you write:
>I've been saying for years that it should be possible to create the 
>concept of DKIM-friendly mailing lists. ...

I suppose, if your users are OK with no subject tags, message footers,
or any of the other cruft that list users have taken for granted for
the past 30 years.

The people who brought us DMARC have a new anti-DMARC thing called
ARC that is intended to help recipients guess whether a message with
a broken signature came through a mailing list.  It's a kludge, but
since it's a kludge that Gmail has already implemented, you'll be
seeing more of it.

Returning to the original question, if a message has no DKIM
signature, that doesn't say anything particularly bad, but it does
mean that the sending IP is your main bit of info to decide whether
it's mail you want, which has issues of its own.


PS: details here

PPS: Please spare us pontification about why ARC can't possibly work
unless you're prepared to cite section numbers in the ARC spec
supporting your argument.

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