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 direct spam sources, spammer hosting/DNS, spam gangs and spam support services.
SBL listings are based on Spamhaus' definition of "Spam" meaning "Unsolicited Bulk Email" ("UBE")
(see: The Definition of Spam). Spamhaus does not evaluate the content or legality of spam, merely whether a message is spam by our definition or not. The responsibility for complying with Spamhaus SBL policy and preventing UBE being sent begins and ends with the bulk email sender.
SBL listings are backed up with evidence which has fully 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.
SBL listings are immediate and, in the case of known spam gangs, are preemptive. The SBL does not require warnings or have a 'grace period' and does not require physical evidence of spam received from any specific IP to qualify a listing (in the case of known spam gangs, any IPs under their control are listed on sight). Warnings are however normally sent to block owners and/or Upstreams before listing large netblocks.