On 11/23/2020 1:27 PM, John Levine wrote:
In article <e3d428f4-1a29-4c6f-4a31-96a24a347...@gmail.com>,
Dave Crocker <dcroc...@gmail.com> wrote:
I believe, though, that the intent of ARC is that it be scalable in
ways that manual enumeration of known legit mailing lists and
forwarders is not.
"if you know which hosts are legit" buries an assumption that is
problematic, namely that you know who handled the message. The fact
that a message purports to be handled by a mailing list you trust does
not mean it actually was.
Pretty close, but not quite.
You know that a message came from a mailing list because you have your
list of IPs or DKIM signatures of lists you trust.
Except that was not stated or, really, even implied in the text of the
message I was replying to. Rather, something like that seemed to be
taken as an assumption, but without any clear foundation.
For these kinds of discussions, which are mostly about understanding
these capabilities clearly, accurately, and precisely, the core
requirement is to separate the essential bits of information and the
basis for knowing each bit.
ARC deals with the problem that most list software forwards everything
with a subscriber's address on the From: line and does a lousy job of
spam filtering.
Forgive me but I believe misbehavior by mailing lists has never been
meaningfully documented for this work. Quite the contrary.
List mail has been collateral damage, not because lists have misbehaved
but because they got caught by a spontaneous change in the email service
by some providers.
d/
--
Dave Crocker
dcroc...@gmail.com
408.329.0791
Volunteer, Silicon Valley Chapter
American Red Cross
dave.crock...@redcross.org
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