The Spamhaus Block List
The Spamhaus Block List (“SBL”) Advisory is a database of IP addresses which do not meet Spamhaus’s policy for acceptance of inbound email and therefore from which Spamhaus does not recommend the acceptance of electronic mail.
IP addresses are listed on the SBL because they appear to Spamhaus to be under the control of, or made available for the use of, senders of Unsolicited Bulk Email (“spammers”). The SBL database will normally include IPs identified to Spamhaus’s best ability as likely direct spam sources, spammer hosting/DNS, spam gangs and spam support services. SBL listings are based on evidence which has satisfied the SBL team that the IP address or IP range is under the control of a spammer, spam operation or a spam support service and represents an unwanted nuisance or threat to mail systems using the SBL.