Blacklist (DNSBL) Check
Check whether an IP address or domain is listed on public DNS blacklists.
Free • no sign-up • results run live in your browser via public DNS resolvers.
What is a DNS blacklist?
A DNSBL (DNS-based Blocklist), also called an RBL (Realtime Blackhole List), is a list of IP addresses reported for sending spam or abuse. Mail servers query these lists in real time and may reject or flag mail from listed IPs. If your mail isn't being delivered, a blacklisting is a common cause.
About this tool's coverage
This checker runs entirely in your browser through public DNS resolvers. That keeps it fast and private, but it has one honest limitation: some major lists — notably Spamhaus and Barracuda — refuse queries that come from large public resolvers, so they can't be checked from a browser-based tool. We check a curated set of blacklists that do answer public queries. For authoritative results on the blocked lists, query them directly from your mail server's own IP.
Frequently asked questions
Each blacklist has its own delisting process — visit the specific list's website and follow its removal instructions. First fix the underlying cause (compromised account, open relay, or spam), or you'll be relisted.
Spamhaus and some other large lists block lookups coming from public DNS resolvers like Google and Cloudflare. A static, browser-only tool can only use those public resolvers, so those lists are unreachable here.
Mail blacklists work on IP addresses. Enter your mail server's sending IP. If you enter a domain, we resolve it to its IP first.