Documentation forEngineer's Toolset

Spam Blacklist

DNS blacklists or spam blacklists are popular tools used by e-mail administrators to help block unsolicited e-mails. A DNS blacklist server maintains a database of IP addresses which are known sources of spam. The idea is, if an IP address has sent spam in the past, it will be likely to send more spam in the future. By configuring e-mail servers to consult DNS blacklists before accepting an e-mail message, administrators can block a large percentage of incoming spam.

With SolarWinds Spam Blacklist you can test the IP addresses of your e-mail servers, and verify that the servers have not been blacklisted. By verifying your blacklist status, you can be sure other e-mail systems which also use blacklist servers will not be blocking e-mail from your system.

One problem that could be detected by monitoring blacklist servers would be when one of your end users receives a Trojan Horse virus which uses the corporate servers to send spam or copies of itself on to other e-mail systems. As a result of the mass mailing caused by the virus, your corporate e-mail server becomes blacklisted. Other business partners begin to block your e-mail because of your blacklist status. You need to know that you have been blacklisted so you can track down the reason why, fix the problem, and then send a request to the blacklist administrator that your address range be removed from the blacklist.

Another use for the SolarWinds Spam Blacklist checker is for determining which blacklist servers would work best on your corporate e-mail server. You can test the source IP addresses of recently received spam and determine which DNS blacklist servers most effectively block the spam. You could also see which blacklist servers are needlessly blocking IP addresses of e-mail servers you need to receive e-mail from.

Scan DNS blacklist servers

  1. Click File > New Address List.
  2. Click Edit > Add Address.
  3. Enter the IP address or host name of the servers you want to add to the list.

    To add more servers, press Enter after each new server.

    You can enter domain names (, host names, and IP addresses.

  4. Click OK.
  5. Click Address > Start Blacklist Scan.

Remove servers from a blacklist

If your servers have been added to a blacklist, contact the blacklist administrator for instructions about getting your addresses removed from the list. Many times there are instructions for doing this on the blacklist server website.

Report a server that is sending spam

You can forward the e-mail to a blacklist server to be added to their list. Most blacklist servers post reporting instructions on their websites. You can also create your own blacklist and add the IP address to this list.

  • Color-coded addresses: when adding addresses to the list, addresses that cannot be resolved will be highlighted in red. Addresses that are successfully resolved show in green.
  • Right-click functionality: when you right-click a server in the Blacklist Servers tab of the Settings dialog, you see additional options to add, edit, or delete servers.
  • Expand/Collapse All at the same time: if you press and hold the CTRL button while clicking on the + or - buttons, everything at that same level will expand/collapse.