Re: [Emailcore] Delivered-To issues

[Dave Crocker <[e-mail]>]

On 1/1/2021 8:24 AM, Dave Crocker wrote:
> 
>       Should the recipient's MUA have access to the /sequence/ of RCPT TO
>       addresses used to get to them?


If the recipient MUA is to have access to the sequence of RCPT TO 
addresses, there are two ways to record this:

    1) A single Deliver-To: header field, showing the (full) sequence

    2) A sequence of Deliver-To: header fields, with each one showing 
one RCPT TO address.

The second would echo the approach taken for Received: header fields, of 
course.  It seems the easier choice.

Any site performing the delivery transition of responsibility, from the 
MHS to the addressee's control, slaps a Deliver-To: header field, with 
that one address on it.

The MUA can construct the sequence by scanning for these header fields, 
from botton to top of the header.

Thoughts?

Also, I think I've seen some expression of concern about *privacy* 
sensitivities, in showing previous Delive-To addresses.  I'm not finding 
myself understanding that well enough to write anything about it.  Can 
we get some discussion of it?


d/

ps. There often is confusion about what 'delivery' means.  This was a 
point of very focused discussion, during the development of RFC 5598, 
with a few folk driving home the rather unusual realization that it does 
not take place during a communication exchange, but takes place /within/ 
the MDA:

> 4.3.3.  Mail Delivery Agent (MDA)
> 
>    A transfer of responsibility from the MHS to a Recipient's
>    environment (mailbox) is called "delivery".  In the architecture, as
>    depicted in Figure 5, delivery takes place within a Mail Delivery
>    Agent (MDA) and is shown as the (D) transition from the MHS-oriented
>    MDA component (hMDA) to the Recipient-oriented MDA component (rMDA).



-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net