IP Blacklist Check
Mail servers and security systems consult DNS blacklists (DNSBLs) before trusting an IP address. This tool queries the five major lists (Spamhaus ZEN, SpamCop, Barracuda, PSBL and UCEPROTECT) in real time and tells you whether an address is flagged. Your own IP is checked by default, and you can test any public IPv4.
What is an IP blacklist?
A DNS blacklist (DNSBL) is a constantly updated database of IP addresses caught sending spam or attacking servers. Mail servers query these lists in real time for every incoming connection: if your IP is listed, your email may bounce or land in spam folders. Spamhaus alone protects billions of mailboxes, so a listing there has real consequences.
Why would my IP be listed?
Four common reasons, and most aren't your fault. A device on your network may be infected and quietly sending spam. Your IP may be shared with many users (CGNAT, common on mobile networks) and someone else earned the listing. Your dynamic IP may have belonged to a spammer before you, leaving you their reputation. Or your mail server really is misconfigured, for example as an open relay.
How to get delisted
First, fix the cause: scan your devices for malware, secure your router, and stop any bulk-mailing software. Then request removal from each list individually, since every DNSBL has its own delisting page (Spamhaus and Barracuda have lookup-and-remove forms, and some lists auto-expire entries after days or weeks). If your IP is dynamic, restarting your router may simply assign you a different address. For stubborn listings on a residential IP, contact your internet provider.
Frequently asked questions
Does a blacklisted IP affect my web browsing?
Rarely. DNSBLs are consulted almost exclusively by mail servers, so the main symptom is email being rejected or marked as spam. A few strict firewalls and forums also check them, which can occasionally trigger extra captchas, but normal browsing isn't blocked by a DNSBL listing.
Why is my IP listed when I did nothing wrong?
Shared and recycled addresses are the usual cause. On mobile and CGNAT connections, thousands of users share one IP, so one bad actor taints everyone. On dynamic connections, you may have inherited an address a spammer used last month. The listing is about the address's history, not about you.
How long does delisting take?
It varies by list. Some entries expire automatically within days once the spam stops. Manual removal requests are usually processed within hours to a few days. Listings tied to ongoing abuse keep coming back until you fix the underlying cause, usually an infected machine or an open relay.