The SORBS (Spam and Open Relay Blocking System), owned and operated by Proofpoint, Inc., provides free access to its DNS-based Block List (DNSBL) to effectively block email from more than 12 million host servers known to disseminate spam, phishing attacks and other forms of malicious email. The list typically includes email servers suspected of sending or relaying spam, servers that have been hacked and hijacked, and those with Trojan infestations. In an attempt to provide preemptive protection, SORBS also lists servers with dynamically allocated IP addresses.
The SORBS New list is a database of IP addresses that have recently been suspected of sending or relaying spam, servers that have been hacked and hijacked, servers with Trojan infections, and servers with dynamically allocated IP addresses. IP addresses remain on this list until no spam has been detected for this IP address by SORBS in a 48 hour period. After that 48 hour window where no further spam is detected for that IP address, the IP will be removed from this list and subsequently listed on SORBS SPAM.