Real-Time Blackhole List

What Does Real-Time Blackhole List Mean?

Real-time blackhole list (RBL) is a dynamic list of IP address owners that are active spammers or spam sources. The RBL may include Internet service providers (ISP) with customers that are known spammers or ISP servers that are hijacked for spamming purposes.


RBL is also known as a DNS Black List (DNSBL).

Techopedia Explains Real-Time Blackhole List

The majority of spam is the result of online advertisements and unsolicited bulk email (UBE). When spam is delivered, the forwarding IP address is added to the RBL.

The RBL prevents system abuse by halting spam. However, the blacklisting process must be handled carefully. It cannot prohibit appropriate or authentic source connections or open-source networking. If an ISP subscribes to the RBL, the ISP may determine which IP addresses should be blocked and added to the RBL. If an IP address matches an IP address listed on the RBL, the connection is automatically dropped.

The RBL was first implemented by the Mail Abuse Prevention System (MAPS), which was acquired by Trend Micro in 2005. Trend Micro adheres to strict guidelines and policies in its continuous effort to nominate and remove spam IP addresses from its blackhole data listings.


Related Terms

Margaret Rouse

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.