Blacklist Checker (DNSBL)
Check whether an IP is on spam blacklists.
DNS blacklists (DNSBL or RBL) collect IP addresses associated with spam or abuse. If your mail server's IP appears on one, your emails may be rejected or marked as spam. This tool queries several well-known lists for an IP and tells you which ones it appears on.
DNS blacklist FAQ
A DNSBL (DNS-based Blackhole List) is a list of IP addresses with bad reputation (spam, malware, compromised networks) that is queried via DNS. Mail servers use it to decide whether to accept email from an IP.
Common causes are: sending spam (sometimes from an infected machine), a misconfigured mail server (open relay), or being in a dynamic IP range that many lists block by default.
First fix the cause (clean the malware, close the open relay). Then each list has its own delisting procedure on its website; some remove the IP automatically after a period without abuse.
Some lists (like Spamhaus) block queries made through large public DNS resolvers and require your own resolver or a subscription. In those cases we can't query them from here and they're marked as unavailable.
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