The Spamhaus Block List ("SBL") Advisory is a database of IP addresses from which Spamhaus does not recommend the acceptance of electronic mail.

The SBL is queriable in realtime by mail systems thoughout the Internet, allowing mail server administrators to identify, tag or block incoming connections from IP addresses which Spamhaus deems to be involved in the sending, hosting or origination of Unsolicited Bulk Email (aka "Spam"). The SBL database is maintained by a dedicated team of investigators and forensics specialists located in 10 countries, working 24 hours a day to list new confirmed spam issues and - just as importantly - to delist resolved issues.

SBL Policy

For listing policy and delisting procedure please see SBL Policy and SBL Delisting Procedure

CSS component

The Spamhaus CSS is part of the SBL. CSS listings will have return code 127.0.0.3 to differentiate from regular SBL listings, which have return code 127.0.0.2.

SBL Usage

For information on how to use the SBL to protect your mail server or network, see the SBL FAQs. The SBL is used both as a sender IP blocklist and as a URI blocklist (SBL is very effective as a URI blocklist). The SBL is included as part of the Spamhaus ZEN combined blocklist.

Before including this blocklist as part of your mail server's spam filters please see Spamhaus's DNSBL Usage Terms to check if you qualify for free use.