Email server (IP) blacklist check

DNSBL or DNS BLacklists is a software mechanism that prevents spamming IP addresses from continuing to spam. How does a DNSBL work? The receiving mail server sends a simple DNS query with the sender's IP address to DNSBL and if it receives a response with a record (usually pointing to 127.0.0.*), it refuses to communicate with the sender. On this page you can test if your IP address or mail server is not listed on some of DNSBL.