Free tool

Is your mail server blacklisted?

Check any IPv4 address or hostname against the major DNS blocklists — Spamhaus ZEN, SpamCop, Barracuda and UCEPROTECT — in a single lookup.

We query Spamhaus ZEN, SpamCop, Barracuda and UCEPROTECT — the lists that actually drive mail rejection.

A listing usually means spam was seen from that IP — open relay, compromised account or shared hosting neighbor.

IPv6 and mail flow live elsewhere: DNSBLs cover IPv4 only, so we resolve hostnames to their A records.