Re: homework, not an experiment, draft-crocker-email-deliveredto

On 8/6/2021 12:32 PM, Viktor Dukhovni wrote:
> On Fri, Aug 06, 2021 at 11:56:50AM -0700, Dave Crocker wrote:
> 
>>> If an MUA wants to learn the envelope recipient address to which the
>>> message was sent (by the immediate upstream MUA or relay) then Delivered-To
>>> is not the right header for that.  That's why Exim has Envelope-To, while
>>> Postfix has "X-Original-To:", both of which are intended for consumption by
>>> tools like fetchmail.
>>
>> So you are saying that it is not possible for one Delivered-To to show
>> the actual address it has been delivered to, followed by another
>> Delivered-To that shows a local transformation to an internal delivery
>> string?
> 
> Well, since "Delivered-To:" is for MTA-private use (loop detection) and

Sorry.  I missed hearing about the documented rule that restricts it use 
this way.


> (by default) records the internal envelope recipient passed to the LDA,
> rather than the input envelope recipient from the sending agent, it was
> deemed appropriate to conflate these into a single header.

It's not conflating.  It is, arguably, exactly the same use.

Note that gmail, for example, merely puts the .... delivery address... 
into the field.

The claim that this field gets some sort of mystical, obscure token has 
yet to be document.  So far, all that has been shown, beyond a simple 
email address, is some descriptive text.  Before a string in the form of 
an email address, which might well be the delivery address.

> 
>> Or are you saying that Delivered-To has nothing to do with delivery?
> 
> I am saying that "Delivered-To" is used for detecting loops in case the

That's nice, but it doesn't answer my question.


d/

-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net