Blacklist Checker: Free Domain & IP Check

A blacklist checker shows whether the IP address behind your domain appears on email spam blocklists. Enter a domain such as example.com and this free tool finds its IPv4 address, queries more than 20 DNS blocklists, and returns an overall status plus a list-by-list table, so you know exactly where to start fixing a problem.

What Is a Blacklist Check for a Domain or IP?

A blacklist check looks up an IP address on DNS-based blocklists (DNSBLs), which are public databases of addresses linked to spam, malware or abuse. Mail servers consult these lists when deciding whether to accept, junk or reject an incoming message.

The lookup works through DNS. The IP is written in reverse (203.0.113.25 becomes 25.113.0.203) and the name of a blocklist is added to it. If the list answers with a record, the IP is listed. If it answers that nothing exists, the IP is not listed.

Domains are not listed directly in this process. The tool first translates your domain into the IP address it points to, then checks that address. If your website and mail server sit on different IPs, check the domain that points to the mail server.

Why does it matter?

A listing on a major blocklist can send your messages to spam or cause them to bounce, even when your content is fine. Password resets, invoices and order confirmations are the first to go missing, and customers usually notice before you do.

How to Use the Blacklist Checker

You only need a domain name. The check takes a few seconds, and you can run it as often as you like.

1. Type your domain into the field that shows the example.com placeholder. Use the bare domain or a hostname such as mail.example.com. Leaving out http:// is fine.
2. Press the submit button next to the field. The button shows a checking message while the lookups run.
3. Read the overall status banner at the top: a listing found, unverified, or no listing observed.
4. Note the domain name, the IP address it resolved to, and the count of clean lists out of the total checked.
5. Scroll to the table and find any row marked as blacklisted. Each row gives the blocklist name and the response it returned.
6. Use the link at the bottom of the results to run another check, for example on a second domain or after you have made a fix.

Worked Example: Reading a Real-Style Result

Suppose you send newsletters from news.example.com and open rates suddenly drop. You enter that hostname and the tool resolves it to 203.0.113.25, a documentation address used here for illustration.

The results show 20 / 21 with no listing observed, and one row marked blacklisted on a UCEPROTECT list. The banner turns red and says the IP has an email DNS blacklist listing.

Here is how to interpret that. One listing out of 21 is not a disaster, but the lists differ in weight. A listing on a single-address list points to your own sending behavior. A listing on a broader network-level list can mean other customers sharing your provider's range caused it. Your next step is to read that list's own policy page and decide whether to request removal or contact your hosting provider.

How to Read and Act on Your Results

The tool returns one of three overall states, and each one calls for a different action.

Listing found (red)

At least one blocklist returned a positive response for your IP. Note which lists flagged you. Major lists such as Spamhaus ZEN, SpamCop, Barracuda and CBL carry the most weight with mailbox providers. Smaller regional lists matter less, but a pattern of several listings suggests a real problem such as a compromised account or an open relay.

Unverified (yellow)

One or more lists did not give a usable answer. An unavailable lookup is not a clean result, so do not treat this as a pass. Wait a few minutes and run the check again. If the same list keeps failing, check it manually on that list's website.

No listing observed (green)

None of the queried lists returned a listing for that IP. This is a good sign for email deliverability, but it only covers the lists shown in the table. It does not say anything about whether your website is safe to browse.

What to Do If Your IP Is Listed

Fix the cause first, then request delisting. Asking for removal before the problem is solved usually gets you listed again within days.

• Find the cause. Common causes are a hacked mailbox or website contact form sending spam, a misconfigured server relaying mail for anyone, a purchased or old mailing list full of bad addresses, and high spam complaint rates.
• Secure the source. Change passwords, update plugins and scripts, and close any open relay.
• Check your email authentication. Make sure SPF, DKIM and DMARC are set up correctly for your sending domain.
• Follow each list's removal process. Every blocklist has its own page and rules. Some expire listings automatically after a quiet period, and some allow a self-service request.
• Retest. Run the checker again after you submit a request. Delistings can take from minutes to a couple of days.

If your IP belongs to a shared hosting range or a cloud provider, you may not be able to fix the cause yourself. Contact the provider and ask for a clean IP or for them to handle the delisting.

Who Should Use a Domain and IP Blacklist Checker?

Anyone who depends on email reaching an inbox gets value from a quick check. Typical situations include:

• Marketers whose campaign open rates fall sharply for no clear reason.
• Store owners whose order confirmation emails bounce or land in spam.
• Web developers launching a new server and wanting to confirm the IP is clean before sending mail.
• Agencies auditing a new client's domain as part of a technical review. Pair this with the bulk domain age checker to see how established each domain is.
• Buyers of expired or second-hand domains who want to avoid inheriting a bad reputation. The bulk domain expiry checker helps you track those domains.

Related utilities are collected in the domain tools category, and server-side protections are covered in the security and encryption tools section.

Best Practices and Common Mistakes

Check the right hostname

The most frequent mistake is checking your website's domain when the problem is with the mail server. If you send email through a separate service, enter the sending hostname or check the IP of that server. A clean web server tells you nothing about a different mail IP.

Do not confuse this with other kinds of blacklists

This tool checks email DNS blocklists for IP addresses. It does not check phone IMEI numbers, company watchlists, credit records or browser safety warnings. If Chrome shows a red warning page for your site, that is a separate issue involving malware or phishing detection.

Set a routine

Check after any sudden drop in email delivery, after changing hosts, and before large campaigns. A monthly check is a sensible habit for businesses that send email regularly.

Avoid quick re-submissions

Repeatedly asking for removal without changing anything wastes time and can lengthen the listing on lists that apply penalties for repeat offenses. Fix first, request once, then retest.

Check your certificates too

Email problems often travel with other trust issues. If your mail server also uses TLS, use the certificate decoder to confirm the certificate is valid, issued to the right name and not expired.

Limitations and Accuracy Notes

The checker reports what each list returns at the moment you run it, so a result can change an hour later. It supports IPv4 addresses only, which means a domain that resolves only to an IPv6 address cannot be fully verified and may show as unverified.

Only the first IP address a domain resolves to is tested. If your domain uses several IPs, such as a load-balanced setup, test the others by entering their hostnames. The tool also covers a fixed set of well-known lists, not every blocklist in existence, so a clean result does not guarantee that every provider will accept your mail.

Finally, a listing does not automatically mean you did something wrong. Shared hosting and recycled IPs can inherit a poor reputation from earlier users.

Enter your domain in the field above to see which blocklists, if any, flag its IP right now. Then use the table to decide whether to fix a sending problem, contact your host or simply move on knowing your address is clear.