IP Blacklist Checker
Check an IPv4 address against 15+ major email DNSBL zones.
Ready to Analyze
Enter a target value above or click any sample preset chip to generate real-time diagnostic output.
About the IP Blacklist Checker
The IP Blacklist Checker tests any IP address against 20+ major DNSBL (DNS-based blacklists) commonly used by mail servers to reject spam. Being listed on even one popular blocklist — Spamhaus SBL/XBL, Barracuda, SORBS, SpamCop, UCEPROTECT — can severely damage your outbound email deliverability, cause message rejections at receiving MTAs, and hurt your sender reputation across the ecosystem.
Mail server operators, deliverability engineers, ISPs, cloud providers and SOC analysts run blacklist checks constantly. New cloud IPs frequently arrive already listed because a previous tenant sent spam. Compromised web servers can end up listed within hours of being turned into a spam relay. Even a single spammy campaign from a shared IP can trigger a listing that takes days to clear.
Once you spot a listing, follow each blocklist operator's delisting process — most have a public webform, some require you to prove the underlying issue is fixed, and a few (like UCEPROTECT) automatically expire listings after a set period. Combine this check with our reverse DNS tool to make sure the IP has proper PTR alignment, which is a prerequisite for delisting on many blocklists.
Enter the required value in the input field above (domain, IP, URL, or text depending on the tool).
Click the action button to run the check — results are computed instantly from our edge network.
Review the parsed output, key fields and any warnings shown in the result card.
Copy the result, share the page URL, or jump to a related tool from the sidebar to continue debugging.
- 20+ major DNSBL zones checked in parallel
- Spamhaus, Barracuda, SORBS, SpamCop, UCEPROTECT and more
- Fast parallel queries via edge-hosted DoH
- Direct links to each blocklist's delisting page