Acronym for Spam and Open Relay Blocking System.
SORBS was originally an anti-spam project where
a daemon would check, in real time, all
servers from which it received
e-mail to determine if that e-mail was sent via various types of
proxy and open-relay
servers. SORBS has evolved into SORBS DNSbl (DNS-based
blacklist) which now includes more than 3 million listed hosts that are
considered to be compromised (Web servers which have vulnerabilities that can be
used by spammers).