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

On 8/6/2021 1:43 PM, Viktor Dukhovni wrote:
> On Fri, Aug 06, 2021 at 12:38:24PM -0700, Dave Crocker wrote:
> 
>>> 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.
> 
> Today, the "Delivered-To" header introduced by Qmail, and adopted in
> Postfix and Exim records an internal non-public mailbox address used in
> MTA-to-LDA communication, that only happens to coincide with the
> incoming public envelope address with some frequency.  It is used for
> loop detection by the MTA.

This description has been repeated quite a bit.

It would be good for loop detection to be applied, so that when people 
post statements intended for the current topic, they don't just repeat 
things that have already been covered.  Repeatedly.



>> Note that gmail, for example, merely puts the .... delivery address...
>> into the field.
> 
> Gmail does not appear to rewrite the input recipient address in transit
> from MTA to LDA.  That's a choice they're free to make.

Indeed they are.  But it establishes use of the same field, in ways that 
might be taken to be slightly different than the use that is constantly 
being repeated.

And the current draft covers both of those uses.


> 
>> The claim that this field gets some sort of mystical, obscure token has
>> yet to be document[ed].
> 
> I am communicating its use in Qmail, Postfix an Exim now, for the nth
> [and last] time.  In these MTAs it is a loop detection token, and not an
> address that is expected to be recognised by downstream user agents or
> MTAs.  The only intended audience is the same MTA (or MTA cluster),
> should the message come back around...

Since you are promising not to repeat yourself, does that mean you might 
finally respond to the current question about adequacy of the current 
draft.  Ideally that would include details about concerns with the text. 
  Extra points for suggesting specific improvements.



d/

-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net