Which is what I was trying to say; this really deserves a new 5.4.x code.
As for text, how about:
X.4.8 Destination does not accept mail
The directory server has returned an indication that the
next hop is incapable of accepting mail.
In the case of a DNS lookup, this can be indicated through the
use of a null MX entry [this rfc].
OK with me if it's OK with everyone else.
Meta-question: this code would presumably also apply for domains that
don't exist or have no records (NXDOMAIN or NOERROR with no answers.) I
am not eager to do yet another draft, but it's more generally applicable
than for null MX.
Regards,
John Levine, johnl@xxxxxxxxx, Taughannock Networks, Trumansburg NY
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