DSNs with NOTIFY=SUCCESS are an obvious example. The only thing I care
about is that delivery succeeds, meaning that this is a negotation between
the originator and the delivery server. The submission server and any
relays in between are completely irrelevant, yet due to the current
envelope-exchange design, they dictate the success of that feature.
Well, the OBVIOUS answer to that, is to take the DSN information out of the
envelope and put it into the header. This won't break any existing MTAs,
and the header gets passed through and ignored any MTA which doesn't
understand it.
and you lose your assurance of getting a delivery report, because you have
no idea about whether the ultimate destination MTA supports such a feature.
Keith