https://web.archive.org/web/20170703084224/http://postmaster.tdc.dk/publish.php?id=31787
rbl.zenon.net
private
+ https://www.blalert.com/dnsbl/rbl.zenon.net
http://www.noc.zenon.net/rbl/
+ russian(?)
http://ahbl.org/node
was public until 2015
now private, invite-only