“SORBS has a long and somewhat checkered history. It was created in the early 2000s, with a DNSBL (Domain Name System-based Blackhole List) version coming online in January 2002,” Chandler wrote. “The closure of SORBS does not mark any real turning point in the email security landscape. Although it was one of the oldest DNSBL services, SORBS helped mainly hobbyist email administrators filter spam and other malicious email traffic. However, its controversial history and management issues have made it a source of frustration for many in the industry and depressed its overall use. SORBS listings have not been considered impactful in the email marketing space for many years. A recent consulting client saw fewer than 200 messages blocked over a volume of less than a million.”

Other ways to filter spam

Girish Bhat, a security marketing executive who worked for Proofpoint when SORBS was acquired, said the decisions were influenced by business dynamics and the difficulty in making such a list profitable. 

“For a high growth business like Proofpoint, monetization would have required significant investment, and the ROI was unclear. I believe that the email industry would not have gotten here without DNSBL services such as Spamhaus, SpamCop, SORBS and others. As most of these services originated and are managed by a dedicated individual or individuals with strong opinions, it is likely to alienate a few,” Bhat said. “To Proofpoint’s credit, even after the SORBS acquisition, they did not interfere with its day-to-day operations. Discussions around monetizing SORBS were abandoned quickly. Although SORBS was a pioneer and did serve an important community role in the past, its utility has diminished due to a plethora of other services.”