Spam Blacklist Check
Check an IP address, domain or email against public spam databases (DNSBL/URIBL). For a domain or email the tool also resolves the mail servers and checks their IPs. A listing is a signal, not a verdict.
Check
Summary
Details
How it works
The tool sends DNS queries to public blocklists. An IP address is looked up as a reversed label such as 4.3.2.1.zen.spamhaus.org, a domain as example.com.dbl.spamhaus.org. An answer inside 127.0.0.0/8 means the target is listed, while NXDOMAIN means it is not.
“Blocked” is not “listed”
Operators such as Spamhaus and SURBL refuse queries that come from public or open resolvers and answer 127.255.255.252-255. The tool reports those as Blocked (a resolver problem) rather than as a listing, so a “Not listed” result is only meaningful when the queries were answered.
IPv6
Most reverse DNS blocklists publish no IPv6 zone, so IPv6 addresses are shown as Not supported instead of being queried.
What a listing means
A blocklist is a reputation hint shared by many mail systems. Being listed does not always mean spam: shared hosting, a recycled address or a single compromised sender can cause it. Use the list operator's own lookup page to request delisting, and keep PTR, SPF, DKIM and DMARC in order.
Privacy
Checks are resolved by the OrbitNet backend and are not tied to your visitor profile. Query answers are cached briefly to avoid hammering the list operators. Unlike other network tools, the blocklists are queried from the server, so the target is disclosed to each public list.