I discovered it when I was disallowed to register at Debian.
So I wondered why - since the server in the boys room has no mail setup whatsoever. And found out why:
SORBS also lists servers with dynamically allocated IP addresses.
Well yes I have a viking60.no-ip.org pointing at a box here. But I sure am not spamming so if this alone is enough then this service sux.
I will check out that it has not been hijacked though.
...It looks like using a service like dyndns or no-ip is enough