Lists of DNS-based Blacklists

There are many blacklists, aka blocklists, maintained by various organizations for use in combatting spam. Many such lists are DNS based. I.e. when an email message arrives the receiving email server may check whether the IP address of the system connecting to the server to deliver the message, which will normally be an email server rather than an individual's PC, is in a blacklist, because it has been identified as transmitting spam.

If the receiving email server finds that the sending server is in one of the queried blacklists, email from it will be rejected by the receiving server. Typically, when an email message is rejected because it is on a blocklist, a message will be returned to the sending server with an indication of which blacklist triggered the message rejection.

An IP address may be listed on multiple blacklists. Determining which blacklists an IP address is on could be time consuming. Below is a list of sites that provide a list of blocklists. You can either query multiple blacklists at once from one of the sites listed below or that site provides a fairly comprehensive list of links to various blacklists

  1. Declude
  2. Moensted
  3. Open Directory
  4. Multi-RBL Check
  5. OpenRBL