Blacklist checker · Free tool
Find out if your mail server is on a blocklist.
Check a sending IP or business domain across major spam blocklists (DNSBLs). Every listing includes guidance to request delisting.
- IP addresses and domains scanned simultaneously
- Major global lists: Spamhaus, Barracuda, PSBL & SpamCop
- Delisting recovery instructions for any active listings
Client-side DNS query. Tool inputs and domain lookups are processed in your browser and not stored in any application database.
Check an IP or domain
A domain is resolved to its sending IP and checked against global blocklists.
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Enter a sending IP or domain to verify if any major spam filter has placed it on a blocklist.
DNSBL Query Classifications:
- Not Listed (Clean): The query returned NXDOMAIN, confirming the IP is not flagged on that blocklist.
- Listed (Flagged): An active listing code was returned (e.g. 127.0.0.x), indicating active blacklisting.
- Resolver Restricted (Not Checked): Open recursive resolvers (such as Google DNS) are policy-restricted by upstream providers (e.g. Spamhaus error code 127.255.255.x). This query is recorded as not checked rather than clean.