In most organisations, there is always someone subscribed to a mailing list. So
I see ADSP will fail there "all" the time.
It seems to me the first party signature ties to the From: header, while the
third party signature, ties to nothing.
The elegant solution, would be to tie the third party signature, may be to the
header: List-Unsubscribe:
In both case this would tie the message to an email address, where you can send
queries.
This would allow the mailing list software, to continue to behave as usual and
also respecting the ADSP.
if there is a valid 3p signature, then it can check ADSP to verify the mailing
list take care of its emails, it would then make the 1p signature irrelevant
(ADSP wise) if broken because the from: header does not match and a few headers
have been removed.
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