Check DNSBLs
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Honest note: This page asks our server to query public DNS / RDAP for the value you enter. We do not need file uploads. Do not use this to probe systems you are not authorized to check.
Public DNSBL checks for mail admins
DNS-based blocklists help receivers score or reject mail from listed IPs. Enter a public IPv4 or a domain (we resolve its public A record). We query a small set of well-known public lists via DNS only — no TCP connect to the target, private/SSRF ranges blocked, and requests are rate-limited.
Frequently asked questions
Is this a port scan?
No. We only perform DNS queries against public DNSBL zones. We never open TCP connections to the IP you enter.
Why rate-limited?
DNSBL operators disallow aggressive querying. We throttle to be a good citizen.
False positives?
Possible. Treat listings as a signal to investigate — not automatic proof of abuse.
IPv6?
This tool focuses on IPv4 DNSBLs. Enter an IPv4 or a domain that has a public A record.