DNS Blacklists are used by mail systems to automatically reject email from known spam/malware sources. These blacklists are majoritively automated and both listing and de-listing is an automated process. In the results of this tool, links are given to the blacklist website (if known) so can make enquiries directly with them if your IP is listed. 

It should be noted that whilst GEN do use some of these blacklists, we do not have any influence over them whatsoever. 

IP Address