Viktor Dukhovni: > To disable DNS in Postfix 2.11.0 or later: > > smtp_dns_support_level = none
Using "none" will throw a fatal error because the value is invalid.
The correct value to disable DNS lookups in Postfix 2.11+ is "disabled" i.e.
smtp_dns_support_level = disabled
and if lmtp: lmtp_dns_support_level = disabled
> With earlier Postfix versions:
>
> disable_dns_lookups = yes
>
> I would still deploy DNS even on the isolated network. Just add
> your own root zone, and off you go.
