Check an IPv4 address against common DNS blacklists (DNSBLs).
A DNS blacklist — DNSBL for short, sometimes called an RBL — is a published list of IP addresses associated with spam or abuse. Mail servers query these lists in real time and use the answer to decide whether to accept, filter or refuse a message.
Enter an IP address above to check it against the blacklists this tool queries.
Listings are usually automatic, triggered by observed behaviour rather than a human decision. The most common causes are:
Fix the cause first. Delisting an IP that is still sending spam simply gets it listed again, and repeated requests damage your standing with the list operator.
Check what is actually leaving the server: review mail logs for unexpected volume, confirm no account has been compromised, and make sure the server is not an open relay. Then use the delisting form the list publishes — most operators provide one, and many will remove a first-time listing automatically once the behaviour stops.
Give it time afterwards. Receiving servers cache blacklist answers, so delivery usually improves over hours rather than instantly.
No tool queries every blacklist — there are hundreds, and they vary enormously in quality and in how many receivers actually consult them. A clean result here means the lists we query do not have you, not that no list anywhere does.
Results also depend on where the query comes from. Several major blacklist operators restrict or block queries from public resolvers and cloud providers to prevent abuse of their free tier, so a lookup from a shared server can return an error or an unhelpful answer for reasons unrelated to the address being checked.
A DNSBL is a list of IP addresses published over DNS and associated with spam or abuse. Mail servers query it while a message is arriving and use the result to decide whether to accept, filter or reject that message.
Most often because spam was seen coming from it — frequently from a compromised machine or account rather than deliberately. Other causes include high complaint rates, hitting a spam trap, or sitting in a range that a list covers as a matter of policy, such as residential address space.
Fix the underlying problem first, then use the delisting form the list operator publishes. Removing an address that is still sending spam only leads to a rapid relisting. Many lists remove first-time entries automatically once the behaviour stops.
It varies by operator. Some listings expire on their own after a period of clean behaviour, others stay until you request removal. Even after delisting, receiving mail servers may cache the old answer for a while, so delivery improves gradually.
Generally no. DNS blacklists are consulted by mail servers, so the direct effect is on email delivery rather than web traffic. A separate reputation problem could affect browser warnings, but that is a different system.