Free tool
Enter an IP address or mail server. We query 11 public blocklists and show where the address is listed.
Blocklists (DNSBL) collect addresses that sent spam, attacks or malware. Mail servers query them for every incoming message. If your server is listed, your mail lands in spam or is rejected. The reasons are on the page of the respective list, where you also request delisting.
Besides the eleven lists we query ourselves, a link takes you straight to the free lookup page of Spamhaus, the most important list of all.
First find the cause (open relay, hacked account, malware), then fix it, then request delisting with the list. Many lists delist automatically once nothing has come for a while.
Spamhaus only allows free queries for non-commercial users, for a company like us that also applies to a free tool. Spamhaus does not answer queries via public DNS servers either, so the result would be wrong. The Spamhaus lookup page shows the real status, with reason and delisting.
Most blocklists only list IPv4 addresses. There are hardly any reliable public lists for IPv6.
KVM servers with their own IP and reverse DNS you set yourself: important for mail servers.
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