IP Blacklist Checker (DNSBL)

Check whether a server IP address is listed on spam blocklists. Essential for mail servers and anyone sending email campaigns.

What the blacklist check covers

The tool takes the IP address you enter and checks it against several public DNS blocklists (DNSBLs), where addresses seen sending unsolicited email end up. It queries well-known lists: Spamhaus ZEN, SpamCop, Barracuda, PSBL and s5h. For each list you see whether the address is listed or clean. This is a key reputation indicator for mail servers: mailbox providers rely on lists like these when deciding whether to deliver a message to the inbox, route it to spam or reject it outright. If a list refuses to answer the query, the tool shows "no answer" instead of guessing.

Why your email lands in spam

If your server's IP appears on even one major list, some of your messages stop reaching recipients. There are several ways to get listed, and knowing them helps you avoid a repeat.

  • The server sent mail without recipients' consent or to a purchased list.
  • An account or CMS was compromised and used to send spam.
  • The IP was "inherited" from a previous customer with a bad history.
  • Email authentication records (SPF, DKIM, DMARC) are not set up.

How to get delisted, and why to check a new server

The removal process is called delisting. First fix the cause (close the vulnerability, clean up your mailing list, set up authentication), then request removal through the form on the specific list's website. Each list has its own delisting page and review timeline. Check the IP as soon as you get a new server: IP addresses are reassigned, and you may inherit a damaged reputation before sending a single email. If you do, ask your VPS provider for a different IP. Checking early saves weeks of chasing undelivered mail.

Frequently asked questions

What is a DNSBL?
It is a public database of IP addresses seen sending unsolicited email. Mail servers consult it when deciding whether to accept or reject a message.
Why is my email going to spam if the server is new?
IP addresses are reassigned, and a new server can inherit a previous customer's bad reputation. Check the address against blocklists as soon as you get it.
How do I get off a blacklist?
First fix whatever caused the listing, then submit a delisting request through the form on that list's website. Each list reviews requests under its own rules and timeline.
How do Spamhaus, SpamCop, Barracuda and PSBL differ?
They are independent lists with their own listing criteria. Mailbox providers weigh them differently, so it pays to check several at once.
Do SPF, DKIM and DMARC keep me off blacklists?
These records authenticate the sender and reduce the risk of messages being treated as forged. They improve reputation, but they do not replace the rule of never sending unsolicited mail.
How often should I check my IP against blacklists?
Regularly if the server sends email or newsletters, and always right after getting a new IP. Early detection lets you delist before delivery problems pile up.