Re: [ietf-smtp] New Version Notification for draft-crocker-email-deliveredto-00.txt

[Pete Resnick <[e-mail]>]

On 14 Feb 2021, at 10:09, Dave Crocker wrote:

> 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.

To the contrary: I am perfectly happy if there is no defined order or 
constraint on the order, but I do think it's worth saying that they MAY 
appear in either order (i.e., no implementation should ever act on the 
order that they happen to appear in).

pr
-- 
Pete Resnick https://www.episteme.net/
All connections to the world are tenuous at best