On 12/7/22 2:59 AM, Alessandro Vesely wrote:
ARC is a good forwarding tool.
I question the veracity of that. Mostly around -- what I consider to be -- the priming problem of getting a receiving system to trust an upstream system's ARC signature.
Its semantic differs from DKIM as it implies no claim of responsibility. So it allows an MTA to forward a message as is, according to user's wishes, without bothering about receiver's policy.
I disagree. The forwarding MTA has, can, and will continue to forward messages with or without ARC. What ARC does do is add some information that the downstream receiving MTA /may/ use to make decisions. The presence of ARC itself has no impact on the capability for an MTA to forward messages.
That is, for example, if you don't enforce DMARC the receiver is still able to apply DMARC policies using trusted SPF results. In order to override DMARC policies, IMHO, the forwarder should be whitelisted by the recipient: an activity that could be automated, since forwarding to a different recipient requires prior agreement.
Forwarding to a different recipient does NOT require prior agreement. Full stop.
Any MTA operator can configure their MTA to forward messages to whomever they want completely independently of the downstream receiving MTA's involvement, much less agreement.
Murray said it goes without saying that WGs can fail.
As someone recently said, science experiments sometimes fail to provide the hypothesized outcome. But it's only a failure if we don't learn something from them. Sometimes learning what doesn't work is more important than learning what does work.
-- Grant. . . . unix || die
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