The Spam and Open Relay Blocking System (SORBS) was conceived as an anti-spam project where a daemon would check "on-the-fly", all servers from which it received email to determine if that email was sent via various types of proxy and open-relay servers. The daemon was not particularly well written and served as a lesson in programming for its original author, Michelle Sullivan.

The daemon still exists and works, though with the latest computer piracy by spammers being hijacking by way of Trojan, there are not many servers stopped. If you are interested in the daemon it is available for download and use at: http://www.au.sorbs.net/sorbs/. During November 2001, the daemon was deployed alongside a number of prominent mail servers that received around 1 million emails per day. The result was a database of approximately 78,000 proxy servers collected over a 2 month period.

The SORBS DNSbl was born November 2002. It was felt that by publicizing a list of compromised hosts, the ever-increasing flow of spam through those hosts could be stopped. On the 6th January 2003 the SORBS DNSbl was officially launched to the public.

Since those initial 78,000 proxies the SORBS DNSbl has grown to an astounding 30 million listed hosts (more statistics at: http://www.sorbs.net/home/stats.shtml. SORBS has expanded over the years to include, hacked and hijacked servers, formmail scripts, Trojan infestations (particularly those with backdoors), and more recently made the move to pre-emptively list all dynamically allocated IP address space.

Other SORBS innovations are the SORBS spam firewall, which has in testingu proved to be better than 99.96% accurate at differenciating spam from real email at ISP input speeds.

SORBS provides its lists free for access to the world, and hopes to continue to do so whilst spam is still a significant problem. SORBS itself is just a name and as such hides many organisations' contributions to the world in the fight against Internet abuse, some of the primary data sources for SORBS also feed data to projects such as Team Cyrmu's DarkNet Project with a view to either listing or shutting down as many infected/Trojaned machines as possible. SORBS also provides data feeds to Government organisations such as the Australian Communications and Media Authority, the Australian Federal Police and America's Federal Trade Commission.

If anyone would like to contribute to SORBS or has any suggestions for new detection routines, and/or hosts to be listed, the SORBS team would love to hear from you. Please use the Mail/Contact Form to get in touch and discuss your thoughts.