🚫 DNSBL Blacklist Checker
Check whether an IP address (or mail server) is on a spam blocklist like Spamhaus, SpamCop or Barracuda.
About DNSBL Blacklist Checker
A DNSBL (DNS-based blocklist, also called an RBL) is a list of IP addresses with a poor sending reputation, published over DNS so that any mail server can query it in real time before accepting a message. If your sending IP is listed, your email gets rejected or sent to spam. This tool queries a dozen well-known blocklists at once and shows which, if any, list the address.
Enter an IPv4 address, or a hostname (we'll resolve its A record first). A listed result usually includes a return code and a reason URL explaining why and how to request delisting. Caveat: Spamhaus and some others refuse queries that come from large public DNS resolvers, so a result of "not listed" from a public-resolver lookup isn't always authoritative — confirm critical cases directly with the blocklist operator. To check the records that control whether your mail authenticates, use the Email Deliverability Checker.