// DNSBL
Blacklist Check
Test an IPv4 address against 8 public DNS blocklists (DNSBLs) used by mail servers to flag spam and abuse sources.
// About DNS blacklists (DNSBLs)
A DNS blacklist (DNSBL) is a list of IP addresses that have been reported for sending spam or malicious traffic. Mail servers query these lists in real time and may reject or flag email coming from a listed address, so a listing can quietly wreck your email deliverability.
Addresses get listed for several reasons: sending spam (often from a compromised device), running an open relay, being part of a residential/dynamic range that shouldn't send mail directly, or sharing a hosting neighbourhood with a bad actor. Each blocklist has its own criteria and its own delisting process.
If your address is listed, identify why (secure any compromised machines, stop bulk sending from residential IPs), then follow the specific provider's removal request. Many delist automatically after the problem stops; others require a manual request.
// Frequently asked questions
- Why is my IP on a blacklist?
- Usually because spam or abuse was seen from it — sometimes from a malware-infected device on your network, an open relay, or simply because it's in a residential range not meant to send mail directly.
- How do I get removed from a blacklist?
- Fix the underlying cause first, then use the specific DNSBL's delisting form. Some lists remove entries automatically once abuse stops; others need a manual request.
- What is a DNSBL?
- A DNS-based blocklist — a database of IPs, queried over DNS, that mail servers use to decide whether to accept, flag, or reject incoming email.
- Why do some zones show 'Skipped'?
- Certain blocklists (notably Spamhaus and CBL) refuse queries that come through public DNS resolvers and return an error code. We detect that and mark the zone Skipped rather than showing a false 'listed' result.