Re: [dmarc-ietf] Signaling MLMs

[Scott Kitterman <[e-mail]>]

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.

Scott K