Check your email servers - blackholes.us DNSBL is dead（情報元のブックマーク数）
blackholes.usなDNSBLが死んでいるそうですので迷惑メール対策で使っている人はチェックしたほうが良さそうです。
Aaron let us know about a discussion thread on the NANOG mailing list about issues with the blackholes.us DNS block list (DNSBL):
InfoSec Handlers Diary Blog - Check your email servers - blackholes.us DNSBL is dead
The issue is the maintainer of the blackholes.us DNSBL shut the list down some time back and the IP address space that the DNS servers for it were on was given back to ARIN. That address space has since been re-allocated to a new company and they are getting tired of the continual inbound DNS queries to the IP address of the old server. Apparently they have now stood up a DNS server to answer those queries with a wildcard record that effectively returns "yes, the IP you are inquiring about is a spammer". As a result, lots of mail relays that are still configured to do lookups against this DNSBL are now being told that everyone on the Internet is a spam source.
