Re: Fwd: New Version Notification for draft-crocker-email-deliveredto-05.txt

> On Sun, Aug 08, 2021 at 07:02:02PM +0200, Alessandro Vesely wrote:

> > The new syntax looks puzzling:
> >
> >     "Delivered-To:"  FWS *phrase Mailbox *phrase CRLF
> >                      ; Mailbox is from [SMTP]
> >
> > The presence of phrases around the Mailbox makes this field difficult
> > to parse.  Without angle brackets, the presence of an unquoted "@"
> > being the only difference.  It is puzzling because phrase usage is
> > neither discussed nor exemplified, and IME not seen in the wild.

> Nobody puts unstructured phrases into "Delivered-To".  There are no
> display names in this context, because the payload is derived
> exclusively from an envelope address.  The "phrase" bits are redundant
> and incompatible with current practice.

Unfortunately this is not the case. Here's one example, from last year:

  Delivered-to: mailing list [email protected]

I don't know if this is a thing all Yahoo Groups do/did, but this
particular group did.

Here's an example of one with an interesting local part:

  Delivered-to: [email protected]
  Delivered-to: "eastgate-eastgate:com-eastgate-list"@eastgate.com

Best not assume nobody uses quoted local parts. I also have to wonder
if the [email protected] should have been exposed.

And another interesting one:

  Delivered-to: [email protected]

I again have to wonder if the IETF really wanted that particular internal
address exposed.

In any case, the real question, I think, is not whether or not examples can be
found of incompatible use of this field - they can - but whether we want to
require implementation to support what is best a rare usage. Speaking for
myself, I think the answer should be "no".

				Ned