On Sat 13/Jun/2020 02:45:36 +0200 John Levine wrote:
In article <45af2d9b-a2d9-4d5c-b1fd-aae906d3a...@kitterman.com> you write:
Which still leaves the question of what the value proposition is since
if you trust the source, what more does ARC really do (I suspect that
the answer is more tokens to run through your bayesian or whatever
filter)?
[...]
ARC lets the recipient look back and retroactively do the filtering
the list didn't. As a concrete example, I find that it is extremely
rare for legit mail coming into a list to be DMARC unaligned (as
opposed to mail coming out of the list) so if you can look back at the
ARC chain and demote mail which failed DMARC coming in, you will catch
a lot of spam without a lot of mistakes.
Most of us keep p=none because we'd likely loose deliverability with a strict
policy. In particular, lists' functioning is smoother that way. When DMARC
takes root, non-aligned messages could be filtered inbound by the list
themselves. In this respect, strict policies are more effective, and we should
consider strategies to get there.
I'd guess ARC has more arrows than just retroactive filtering. Anyway, it
remains a tool for very large operators. Mailing lists cannot afford to lose
participation by small operators. Therefore they won't give up rewriting
From:. ARC doesn't help DMARC adoption.
Best
Ale
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