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 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 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.

SBL listings are immediate and, in the case of known spam operations, 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.

The criteria for listing IP addresses in the SBL is:

Notifications of Listings

Spamhaus maintains a database of worldwide Internet Service Providers which includes the ISP's contact address for abuse issues (where known). On creating a new SBL record the SBL database automatically emails a notification of the listing to the ISP's abuse contact (where known).

Delisting

IP addresses are removed immediately from the SBL database upon receipt by the SBL Team of notification from the IP owner (the Internet Service Provider responsible for assigning or routing the IP address) that the reason for listing has been corrected or terminated. See SBL Delisting Procedure for a detailed description of delisting policy and procedure.

Updating

Spamhaus does not perform scans to update SBL records. It is the ISP's responsibility to advise the Spamhaus Project of any changes which affect a listing. On being advised of changes, Spamhaus will endeavor to amend the listing as quickly as possible.

Timeouts

If not removed manually from the database, all SBL records eventually time out and are automatically removed. Each SBL record has a timeout value set by the record Editor as deemed appropriate for the listing. Unidentified spam sources normally have a short time-out of 2, 7 or 14 days, persistent spammers may have a timeout set at 6 months, while known spam gangs with ARIN-assigned IPs will normally have the timeout set at one year or more.