IP Blacklist Checker

See the individual result for an IP address against each specific DNS-based block list checked.

What is an IP blacklist checker?

An IP blacklist checker tells you whether an IPv4 address appears on DNS-based block lists, also called DNSBLs. Mail servers and spam filters consult these lists to decide whether to accept, filter or reject email. If your mail server's address is on an IP blacklist, some of your messages may bounce or land in spam folders.

This tool shows a separate result for each list it checks, so you can see exactly where an address is listed.

How the blacklist check works

A block list is queried through DNS. The tool reverses the parts of the address and asks the list's zone about it: for 203.0.113.7, it asks about 7.113.0.203.bl.spamcop.net. An answer means the address is listed. A "does not exist" reply means it is not. Anything else, such as a timeout or a refused query, is reported as "Unable to check" rather than guessed.

Lists checked

  • SpamCop Blocking List (bl.spamcop.net)
  • Barracuda Reputation Block List (b.barracudacentral.org)
  • SORBS (dnsbl.sorbs.net)

Each list has its own rules for adding and removing addresses, so results often differ between lists. One listing next to two clean results is common.

This is a small spot check across commonly referenced lists, not a complete reputation report. Spamhaus is deliberately not included, because its usage terms restrict queries from public web tools.

How to check an IP blacklist status

  1. Enter an IPv4 address, such as your mail server's sending address.
  2. Press Check Blacklists.
  3. Read the result for each list: Listed, Not listed or Unable to check.
  4. If the address is listed, open that list's website to find the reason and its removal process.

What the blacklist results mean

Listed means the list currently includes the address, usually after spam traps or user reports. Not listed means the list confirmed it does not include it. Unable to check means the query itself failed, so no conclusion can be drawn for that list. A listing is a reputation signal, not proof that the current owner of the address did anything wrong.

How to keep an IP address off blacklists

  • Send email only to people who asked for it, and remove addresses that bounce.
  • Use strong, unique passwords on every mailbox, since hacked accounts are a frequent source of spam.
  • Protect website contact forms so they cannot be used to send bulk mail.
  • Publish SPF, DKIM and DMARC records so receivers can recognise your genuine mail.
  • Give your mail server a PTR record that matches its hostname.
  • Check your sending address now and then, so a new listing is caught before customers notice.

Common uses

  • Investigating why email from your server is bouncing or going to spam.
  • Checking a new server's address before using it to send email.
  • Confirming that a removal request has taken effect.
  • Checking an address quoted in a bounce message.

Common problems and fixes

Your server is listed. Find the cause first: a compromised account, an infected device or a form that sends spam. Fix it, then follow the list's removal process. Some lists expire entries automatically once the spam stops.

A shared host's address is listed. Another customer may have caused it. Ask your hosting provider to investigate, or use a dedicated sending service.

IPv6 address entered. This checker supports IPv4 only, because block list coverage for IPv6 is inconsistent.

Related tools

Frequently asked questions

Why is my IP address on a blacklist?

Usually because spam or other unwanted mail was sent from it, detected by spam traps or user reports. Common causes are a hacked email account, malware on a device, an insecure website form or a previous user of the same address. Fix the cause before asking for removal, otherwise the address is likely to be listed again.

How do I get my IP removed from a blacklist?

Visit the website of the list that shows Listed and use its lookup or removal page. Most lists explain why the address was added and let you request removal once the problem is fixed. Some remove entries automatically after a period without new spam, often a day or two.

Does a blacklist listing mean the IP is malicious?

No. It means the list received reports or detected unwanted traffic from that address at some point. Shared hosting, dynamic home addresses and recycled cloud addresses are often listed because of an earlier user. Treat a listing as a reason to investigate, not as proof.

Why does the checker say "Unable to check"?

The query to that list failed, for example because it timed out or the list refused the request. This is different from "Not listed": no answer means no conclusion either way. Try again a little later, or check the list directly on its own website.

Which blacklists does this tool check?

It checks three commonly referenced DNS-based lists: the SpamCop Blocking List, the Barracuda Reputation Block List and SORBS. It is a quick spot check, not a full reputation report. Spamhaus is not queried because its terms restrict use by public web tools.

Will being blacklisted stop all my email?

Not usually. Each email provider decides whether and how to use each list. A listing on one list may cause rejections at some providers and have no effect at others. If messages are bouncing, the bounce message normally names the list or reason, which tells you where to start.

Can I check an IPv6 address for blacklisting?

Not with this tool. Block list coverage and query formats for IPv6 are inconsistent between providers, so results would not be reliable. Most email is still delivered over IPv4, so check your mail server's IPv4 sending address, which you can find in the header of a sent message.