Now every dns request on that domain resolves to some address [3], creating havoc on mailsevers that did not remove this service from active blacklists.

[1] https://www.dnsbl.info/dnsbl-njabl-org.php [2] https://whois.icann.org/en/lookup?name=njabl.org [3] nslookup anything.dnsbl.njabl.org