What this tool checks
Email blocklists, also called RBLs or DNSBLs, track IP addresses that have sent spam. If your sending IP lands on one, receiving servers may reject or junk your mail. This checker queries several major blocklists at once and shows where your address is listed, where it is clean, and where the list declined to answer. Enter an IP or a mail server hostname and it resolves the address for you.
Frequently asked questions
My IP is listed. What do I do?
Visit the blocklist that lists you and follow its delisting process. First find and fix the cause, such as a compromised account, an open relay, or a misconfigured server, or you will simply be relisted.
Why do some lists show no data?
A few blocklists, including Spamhaus, refuse queries that come through shared public resolvers. When that happens the result is reported as no data rather than clean or listed. It does not mean you are blocked.
Should I check the IP or the domain?
Blocklists work on IP addresses, so check the IP of your sending mail server. If you enter a hostname, the tool resolves it to its IP first and checks that.