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IP blocklist (DNSBL) checker

Checks a sending IP address, or the address of a host name, against public blocklists that receivers use to filter mail. Shows each list’s answer, what it means and where to request removal.

An IPv4 or IPv6 address, or a host name such as mail.example.com.

How this check works

Each list is queried by DNS as described in RFC 5782: the address is reversed and looked up under the list’s zone. An answer in 127.0.0.0/8 means “listed”; no record means “not listed”.

We only query lists whose published terms allow a free public lookup service. Spamhaus, Barracuda and some other well-known lists do not allow this use without a subscription or registration, so they are not included; check them on their own websites.

Answers are cached for 15 minutes. A list that does not answer, or refuses to answer (for example with a 127.255.255.x code), is shown as “not checked” — never as clean.

Limitations

  • A listing does not mean that every receiver blocks you; large mailbox providers mostly rely on their own reputation data.
  • Lists differ: some list single addresses, others whole networks of a provider, and some publish a score rather than a verdict. These are marked separately.
  • Not being listed on these lists does not prove a good reputation: lists not queried here may still list the address.

Frequently asked questions

Why is my IP address listed?

Usually because spam or attacks came from it: a compromised account, website or device, an open relay, or a previous user of the address. Some lists also list whole ranges of a provider when it does not act on abuse reports.

How do I get removed?

Find and fix the cause first, otherwise the address returns to the list. Then use the list’s removal page. Many lists also remove entries on their own after a quiet period; a paid “express” removal is never required for those.

Why is Spamhaus not checked here?

Spamhaus allows free queries only for non-commercial use and refuses queries made through public DNS resolvers, so a public lookup service would need a paid subscription. Use the official lookup at check.spamhaus.org.

Does this check my domain?

No. These lists rate IP addresses. Domains have their own reputation, tracked by mailbox providers and by domain blocklists.