return codes documented
https://spameatingmonkey.com/services
http://uribl.com/
+ lists domains/URIs
+ that appear in spam bodies
+ has whitelist
+ lists IPs
+ that URIs in spam bodies resolve to
+ return codes are documented
+ https://uribl.com/about.shtml#implementation
+ bitmasked
+ 127.0.0.1 is used to signal abusive query behaviour
http://wiki.junkemailfilter.com/index.php/Spam_DNS_Lists
http://www.rbl.jp/allrbl-e.html
http://www.sorbs.net/