Network Tools

Run a blacklist check

Enter one numeric host address. Hostnames, CIDR ranges, ports, private addresses, and link-local addresses are not queried.

Try:

Exactly what is covered

The checker deliberately favors documented, directly queryable public zones over a large but unverifiable provider count. IPv4 gets four sources; IPv6 gets DroneBL only.

DroneBL · IPv4 and IPv6

Signals compromised hosts, proxies, bots, abusive VPNs, and other network-abuse classes. It is not limited to email spam. Return-code classes are decoded individually.

Official usage documentation

SpamCop SCBL · IPv4

A fast-moving list of IPs associated with reported email. SpamCop warns that it is aggressive and recommends scoring or tagging rather than blind rejection.

Official query documentation

PSBL · IPv4

A passive spamtrap list. Its operator says anybody may use the DNS zone and also warns that legitimate mail servers can occasionally be false positives.

Official usage documentation

blocklist.de · IPv4

Recent attacks reported by participating systems, including SSH, mail, web, login, and other services. It is broader network-abuse evidence, not an email-sender verdict.

Official DNS documentation
Not queried: Spamhaus public mirrors are excluded because their free-use policy rejects public/open resolvers, generic or shared hosting, and some commercial use; Barracuda BRBL requires requested access for DNS use. Keyed, paid, scraped, and undocumented sources are also excluded. Use each provider’s own manual lookup if you need those datasets.

How to read the evidence

1Listed

A documented provider return code was received. It describes that provider’s dataset and policy only; review the decoded reason and official lookup before acting.

2Not listed

NXDOMAIN or NODATA was returned authoritatively for that exact zone and address. This is a point-in-time negative result, not proof of safety or deliverability.

3Inconclusive

SERVFAIL, REFUSED, timeout, conflicting authorities, an unknown A code, or an API/network failure never becomes “not listed.” Recheck later or query the operator directly.

4Resolve a listing

Confirm the IP in the bounce or logs, fix compromised hosts or sending practices first, use the provider’s evidence/removal path, then allow for DNS cache and list update delays.

DNSBL status is not broad IP reputation. It does not measure inbox placement, Gmail or Microsoft filtering, engagement, domain reputation, sender scores, geolocation, ownership, routing, malware prevalence, proxy/VPN status across the wider market, or whether an address is safe to trust.