An IP address blacklist is a listing of IP addresses which have been reported to have sent spam. When users mark a message as spam or filters note patterns in a message that have occurred in known spam, the originating IP address of the messages can be added to various blacklists on the Internet. A mail server subscribing to those blacklists will refuse to deliver a message originating on a server with that IP address.
When an IP address has been blacklisted, the destination mail server will reply with a message indicating that the source server's IP address has been blacklisted. The message often contains a link to steps that can be taken to remove the IP address from the black list.
What to Do If You Believe that Your IP is Blacklisted
If your IP address is listed at these resources, you will see something like the following:
The blacklist checker of your choice will identify what lists you are currently on, and generally will provide a link to the list owner's site. In the above example the IP address in question is on the BARRACUDA and ivmSIP blacklists. Clicking on the detail button opens a new window with a link to that resource.
What to Do If Your IP Address Is On a Blacklist
Each blacklist site is going to vary slightly in how they handle an IP listing, and the method in which you can submit a request to be removed from that list. Not all blacklists allow manual removal of your IP address from their list. There are a few blacklists that do not allow requests for removal, and simply state that your listing will be removed after a set period of time barring any further spam activity. There is nothing more that can be done in this case, and you must wait for the allotted period of time.
Most blacklists will allow you to submit a removal request, and typically there are two steps to do so:
Use their tools to search for your IP address in their database. It will return with a result letting you know if you are listed or not, and often the time you were first added to the list as well.
Once you've searched your IP address, the blacklist resource will typically give you information on how to submit a request to be de-listed/removed from the blacklist. The removal can be immediate, or take anywhere from an hour to a week depending on the individual list's policies. These will usually be laid out in the removal request information.
Below is an example of a removal request form from BARRACUDA:
After you've gone through each blacklist to submit removal requests, you can continue to check the status of your listings via a blacklist checker like MXToolBox.com
to see if you're still listed across multiple sites. Note: IP addresses are not immediately removed. It may take anywhere from an hour to a few days before the blacklists are updated.
Once you have corrected the issue that caused your IP to be blacklisted and have cleared your IP from those blacklists, you should take steps to prevent it from happening in the future. To catch spam (or at least limit the impact) before your IP becomes blacklisted, see Adding an Event in SmarterMail to Monitor Mail Spool Activity