> On Jun 28, 2018, at 6:10 PM, li...@mbchandler.net wrote:
>
> I agree about the nameserver, but unfortunately I don't have a choice. I'm
> required to use this one.
>
> I'm not as familiar with DNS as I should be, but is there a temporary error
> code the nameserver could return instead, that would cause Postfix to defer
> this mail?
Yes. Instead of: rcode=NXDOMAIN
Reply with: rcode=SERVFAIL
> Another question. As far as Postfix is concerned, is there a difference
> between a domain with no mx record and a domain where there is an mx record,
> but it's not resolvable?
Yes, there's a difference, specified in RFC5321, so all working
MTAs do the same thing. The former is an implicit MX:
nomx.example. IN MX 0 nomx.example.
leading to delivery attempts to the addresses of nomx.example,
if any. The latter is an error.
--
Viktor.
