Check any IPv4 address (or domain) against 15 spam blocklists + the DNSWL allowlist. Live DNS queries, no caching, no signup.
This tool queries 15 major spam blocklists (DNSBLs) plus the DNSWL allowlist in real time. Each query is a live DNS lookup against the operator's authoritative servers - no caching, no proxying, no third-party intermediary.
For each blocklist, we reverse the IP octets and prepend them to the blocklist's zone, then query a DNS A record:
IP being checked: 192.0.2.5 Reversed: 5.2.0.192 Query: 5.2.0.192.zen.spamhaus.org If A record returns 127.0.0.X > LISTED (the X identifies the sublist) If query returns NXDOMAIN > not listed
Sometimes a TXT record returns the listing reason (e.g., "Currently sending spam, see https://..."). We surface that when present.
Not all listings are equal:
If you're listed on Spamhaus ZEN or Barracuda, take it seriously - fix the root cause and submit delisting requests. If you're only listed on UCEPROTECT-3 or one of the smaller lists, the deliverability impact is minor.
Our complete guide explains the metrics mailbox providers track, the listing-recovery playbook, and how to monitor reputation continuously.
Read the sender-reputation guideSpamhaus SBL listings typically require manual delisting and can persist for weeks if the underlying issue isn't fixed. Barracuda lists usually clear within 24-48h after delisting request. SpamCop ages naturally (24-72h). UCEPROTECT auto-removes after a clean period (typically 7 days). Bookmark this checker and re-test daily during recovery.
Yes - enter a domain and we'll resolve its A record first, then check the resulting IP. Note: DNSBLs operate on IPs, not domains. If your domain has multiple A records, we check the first one returned by your DNS provider. For domain-level reputation, use Spamhaus DBL separately.
Different checkers query different DNSBLs. We check 16, MXToolbox checks ~30, some smaller tools only check 5-10. Listings can also appear/disappear within minutes - DNSBLs update continuously. The most-trusted single signal is Spamhaus ZEN; if you're clean there, you're 90% safe.
No. Queries are processed in-memory and not stored. The DNS queries themselves go to the blocklist operators' nameservers - those operators may log query traffic per their own policies (Spamhaus famously logs and analyzes query patterns). We don't proxy or modify anything in transit.