Re: [dmarc-ietf] Signaling MLMs

[Alessandro Vesely <[e-mail]>]

On Sat 15/Apr/2023 18:10:08 +0200 Scott Kitterman wrote:
> On Saturday, April 15, 2023 11:45:34 AM EDT Alessandro Vesely wrote:
>> On Sat 15/Apr/2023 16:42:32 +0200 Scott Kitterman wrote:
>>> On April 15, 2023 1:55:59 PM UTC, Jesse Thompson <[e-mail]> wrote:
>>>>And the "If a mailing list would like to provide the best customer 
>>>>experience...MUST rewrite" suggestion seems like a reasonable way out of 
>>>>this "interoperability vs reality" standoff.  How about if I soften it up 
>>>>further:
>>>>
>>>>"Any sender (mailing list, forwarder, ESP, or otherwise) which is tasked 
>>>>to send unauthenticated email from an address within a 
>>>>p=reject|quarantine domain it MUST refuse to send the message or send the 
>>>>message using an RFC5322.from address in a different domain."
>>>
>>> That kind of customer experience guidance isn't what goes in an IETF 
>>> protocol specification with normative language.  There can, and probably 
>>> should be, some discussion about that in an appendix, but without the 
>>> MUSTard.
>>>
>>> As I recently mentioned in another thread, the From rewriting trick is 
>>> explicitly contrary to MUST NOT language in RFC 5321 on mailing lists. 
>>> We should quit pretending it's in scope as a component of DMARCbis and 
>>> move on.
>>
>> I hope they amend that passage.  There are several shortcomings in that
>> section.  By the same argument, MLMs shouldn't add List-* header field
>> either.
> 
> Perhaps, but I don't think the fact that when RFC 2321 was updated, they
> didn't make explicit provisions for RFC 2919 and perhaps should have, gives us
> any wiggle room around the fact that From is the one field in the header that
> is specifically called out as not being changed.


That's right.  Yet, that's what everyone does hitting «forward» on a MUA.  Such 
action is indeed exemplified as what a mediator does not do in RFC 5598, near 
the beginning of Section 5.  We're slightly changing Internet mail architecture.

Best
Ale
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