Am 2017-07-05 08:51, schrieb Rick Moen:
> I believe you said that you are running an instance of Unbound as a
> local recursive nameserver. If so, I hope you are listing it first in
> /etc/resolv.conf (perhaps by localhost IP). Anyway, that's where you
> should start looking, to find your problem.

That's right. And my local unbound is the only nameserver in
/etc/resolv.conf

I cannot use other nameservers because my postfix queries some RBLs that
allow only limited numbers of queries (they are free for personal use,
but costs for commercial use).

Jochen