On 2/12/2021 9:03 AM, Pete Resnick wrote:
The examples show Delivered-To: next to the last Received: field, which
implies that Return-Path: is going to get pre-pended after the
Delivered-To: field. If in practice they can appear in either order
(which seems perfectly plausible), that seems like a reasonable thing to
mention. If in practice they always appear in a particular order (which
also seems plausible) and some entity later reading the message relies
on that order (which doesn't seem like a great idea, but weirder things
have happened), that seems like an important thing to say. Either way,
setting expectations seems good.
It's always dangerous to attempt at deriving normative requirements from
examples, of course.
The current text just says to add Delivered-To: to the top and it says
what actor is to do this. I think that has all of what is required
about the field itself.
RFC 5321 (Section 4.1.1.4) has similar detail, in its 5th paragraph.
Guessing at a requirement about the combination of the fields goes quite
a bit beyond either of the specifications.
One could imagine a usage document discussing this, but there does not
seem to be a benefit in creating a constraint about their combination in
this specification.
d/
--
Dave Crocker
Brandenburg InternetWorking
bbiw.net
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