But I don't think it's clear that doing so would change anything at
the recipients MX. As a concrete example, if two subscribers to a
mailing list send mail to the list, one DKIM signed and one not,
and the list then signs each message and sends it to the recipient,
is there any reason that the recipients MX would treat those two
messages differently?
Yes.
I still don't get it. The sorting rules I use on mailing lists are
based on the list's identity using List-ID: headers or subject tags,
not the individual sender. People will, I hope, correct me if I'm
wrong, but I'm pretty sure that's typical of existing practice.
It's possible to add all sorts of extra stuff to messages to pass
through all sorts of complex assertions, but my list sorting works
perfectly well now. What problem for the list recipient are we
solving with this proposed extra mechanism?
To address one possibility, none of the lists I'm on have significant
problems with bad guys sneaking messages onto the lists by pretending
to meet the criteria for posting messages to the list. Back in the
Krazy Kevin era, 15 years ago, that was a problem but list owners and
managers have dealt with it quite successfully. If the claim is that
it'll become a problem again, I think it's fair to ask why, since list
owners and managers have dealt with it in the past, they wouldn't
continue to do so.
R's,
John
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