I don't recommend this kind of setup because I get the heebie-jeebies when
I contemplate the possible interoperability problems. Richard's and Ned's
comments above confirm my fears.
Same here. My MTA does single recipient deliveries, which on today's net
where the bit rates have increased by orders of magnitude over the past 20
years but the round trip delay hasn't changed at all, typically gets mail
delivered faster anyway, while making all of these issues moot.
Nonetheless, multiple recipient deliveries aren't going away, so I think
it would be if nothing else a useful exercise to pin down what we think
clients should do given various combinations of return codes. Then
perhaps we can both see how this compares to what they actually do, and
offer some advice to both clients and servers to improve interoperability.
Incidentally, MAAWG is working on a project to clarify the meaning of
return codes, and that might be relevant.
Regards,
John Levine, johnl(_at_)taugh(_dot_)com, Taughannock Networks, Trumansburg NY
"I dropped the toothpaste", said Tom, crestfallenly.