does not seem to have a DNSBL (anymore)
might be incorporated into spamhaus?
does host other databases about threats
+ https://puck.nether.net/or/
+ website is dead
00_NEEDS_RECHECK
https://antispam.imp.ch/
no usage policy
return codes documented: binary
http://mailspike.net/usage.html
reputation-based
- https://puck.nether.net/or/
- policies on website
http://www.isipp.com/email-accreditation/iadb-query-instruction/
requires signup
not quite a usage policy, but seems ok