DNS Blacklist Check
Check whether a hostname or IP is listed on major DNS-based spam blocklists (DNSBLs).
Queried directly against each blocklist's own DNS zone, right now — not a cached or third-party reputation score.
Enter a host or IP to check
Each blocklist is queried live — listed, not listed, or unreachable.
A DNSBL (DNS-based Blackhole List, also called an RBL) is a list of IP addresses flagged for sending spam or exhibiting other abusive behavior, published as a queryable DNS zone. A mail server checks an incoming connection's IP against these zones before accepting the message; a listing on a widely-trusted one is often enough on its own to get mail silently rejected or routed to spam.
Each provider maintains its own criteria and its own zone, so a listing on one does not mean a listing on all of them — a single compromised mail relay, a shared hosting IP with a noisy neighbor, or a misconfigured server can trigger a listing on one list while staying clean elsewhere. This check queries several major zones directly and reports each one's answer individually rather than a single blended score.
Delisting is provider-specific: most blocklists offer a self-service removal request once the underlying cause (an open relay, a compromised host, a spam campaign) has actually been fixed, but a repeat offense usually makes the next delisting harder to get.