IP blacklist checker
Enter an IPv4 address to check it against 17 major DNS blacklists used by email providers and security tools globally.
About this tool
A DNS-based blocklist, or DNSBL, is a list of IP addresses associated with spam, malware, or compromised hosts, published in a form mail servers can query in milliseconds during an SMTP conversation. Receiving servers consult them before accepting a message, so a listing does not send your mail to spam — it usually causes the message to be rejected outright at connection time. The lists are not equivalent in weight or in temperament. Spamhaus is consulted by a large share of the world's mail infrastructure and a listing there has immediate, broad consequences; smaller and more aggressive lists are used sparingly and matter far less. Listings happen for reasons that are often not your fault: a shared hosting neighbour sending spam, a compromised account, a misconfigured mailing list, or simply an address inheriting the reputation of whoever held it before you. This tool queries seventeen major blocklists at once for an IPv4 address and shows which report a listing, with a link to each provider's delisting process for any positive hit.
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Enter an IPv4 address in the input field.
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Click Check — the tool queries 17 major DNS blacklists simultaneously.
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Green rows mean the IP is clean on that list; red rows indicate a listing.
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Click the blacklist name for any positive hit to visit the provider's delisting page.
Check whether your mail server's IP is blacklisted if email is bouncing or going to spam.
Verify a new IP before assigning it to a mail server or public-facing service.
Investigate a suspicious IP from server logs to see if it has a history of spam or abuse.
Clean IP
8.8.8.80/17 listed — IP is clean across all checked blacklistsBlacklisted mail server
192.0.2.13/17 listed — Spamhaus ZEN, SpamCop, SORBSCheck own mail server
203.0.113.501/17 listed — UCEPROTECT L1 (delisting available)Listed on a blocklist nobody seems to have heard of
Cause: There are hundreds of DNSBLs and many have negligible adoption or list entire ranges on principle. A hit on an obscure list rarely has any effect on delivery.
Fix: Prioritise by consequence. A Spamhaus listing needs immediate attention; a listing on a low-adoption list usually needs none. Check whether your actual bounce messages name the list before acting.
Delisted successfully but mail is still rejected
Cause: Receiving servers cache DNSBL responses, and rejection may be driven by a different signal entirely — a failing SPF or DMARC record, poor domain reputation, or a separate list you have not checked.
Fix: Allow time for caches to expire, then read the exact bounce message, which names the reason and often the list. Verify SPF, DKIM, and DMARC separately, since domain reputation is now weighted more heavily than IP reputation.
Relisted shortly after delisting
Cause: The underlying cause was never fixed. A compromised account, an open relay, a malware infection on the network, or a misconfigured form that lets spammers send through it will trigger a new listing within days.
Fix: Find and fix the source before requesting delisting. Audit outbound mail volume, check for accounts sending without authentication, and confirm the server is not acting as an open relay.
These answers explain common blacklist check tasks, expected input formats, and edge cases so both visitors and search engines can understand what this tool does.
What is a DNSBL?
A DNS-based Blackhole List (DNSBL) is a database of IP addresses with a history of spam, malware hosting, or other abuse. Email servers query these lists in real time to decide whether to accept or reject incoming mail.
Which blacklists are checked?
17 lists including Spamhaus ZEN, Barracuda, SpamCop, SORBS SPAM, SORBS HTTP, UCEPROTECT L1/L2, DroneBL, NiX Spam, Backscatterer, SpamRATS (Spam/Dyna/NoPtr), Mailspike, PSBL, LASHBACK UBL, and Truncate.
Why is IPv6 not supported?
The DNSBL protocol works by reversing the octets of an IPv4 address and appending the blacklist zone. This mechanism does not map cleanly to IPv6 addresses, so most major DNSBLs only index IPv4 addresses.
My IP is listed — what do I do?
Visit the blacklist's website and use their delisting form. Spamhaus and most other operators provide a self-service removal process once the underlying issue (spam, malware, open relay) has been resolved.