A similar but unrelated term is ORB (Object Request Broker).
ORBS (Open Relay Behavior-modification System) is (or possibly was - as of June 7, 2001, it was not operating) a volunteer-run New Zealand-based organization that operates an anti-spam screening service. The ORBS database tracks e-mail (specifically SMTP) servers that allow third-party relay (TPR), a practice that makes it possible for any sender to connect to the server from anywhere and forward volumes of unsolicited bulk e-mail messages. As a further precaution, ORBS also tracks networks that have set up processes to prevent verification of third-party relay permission, since administrators sometimes find it easier to block ORBS testers than to address security problems.
In the first years of the Internet's operation, third-party relaying was a necessary and accepted means of routing messages. Although technological advances have made third-party relaying no longer required, many servers continue to maintain open relays, according to ORBS, in the "Internet's spirit of cooperation." According to ORBS, however, an open relay now falls into the category of "attractive nuisance." The organization claims that since 1995, the culture of the Web has changed dramatically, with the result that open relays became vulnerable to spammers looking to make a quick profit through bulk junk mail.
ORBS maintains a blacklist of Internet service providers (ISPs) and other organizations found in violation of their criteria, a practice that is somewhat controversial because the targeted enterprises often believe they have been listed unfairly. In one recent instance, a New Zealand high court ruled that ORBS must remove Xtra mail servers (owned by Actrix, an New Zealand-based ISP) from their list of suspect servers. ORBS is in occasionally acrimonious competition with a similar system based in California, the Mail Abuse Prevention System (MAPS). The two organizations clashed when ORBS blacklisted Above.net (an ISP owned by Paul Vixie, who also runs MAPS) as an open relay.