Can we not turn this discussion into one that instead say:
If you want to have this result, configure DNS this way:
Not really. I want to give advice to people who are writing MTAs. They
need to deal with whatever they find when they're trying to deliver mail.
As I hardly need to tell anyone here, we need to deliver mail on the
Internet we have, not the Internet we might want or wish to have at a
John Levine, johnl(_at_)taugh(_dot_)com, Taughannock Networks, Trumansburg NY
"I dropped the toothpaste", said Tom, crestfallenly.