Our blacklist checker is a tool that assesses a mail server’s IP address by cross-referencing it with more than 100 DNS-based email blacklists, often referred to as Real-time blacklists, DNSBLs, or RBLs. When a mail server’s IP address is blacklisted, there is a risk that some of the emails sent from that server may not reach their intended recipients. These email blacklists serve as a widely used method for minimizing the impact of spam emails. If you are having troubles with your own emails not getting through to their intended recipients you can also check to see if your address is blacklisted in any database.