Free DNS tool

Blacklist Checker

Scan a domain or IP address against the DNS blacklists that mailbox providers actually consult. A listing on any of them can quietly sink your delivery, so see exactly where you stand and what to do next.

No login required. We query live DNS blacklists and never store your domain.

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GradeFull reputation reportSPFCheck your SPF recordDMARCCheck your DMARC policy
Blacklists, explained

What is an email blacklist?

An email blacklist, also called a blocklist or DNSBL (DNS-based blacklist), is a published database of IP addresses and domains that have been flagged as sources of spam or abuse. Mailbox providers such as Gmail, Yahoo, and Microsoft, along with most corporate mail filters, query these lists in real time while deciding whether to accept, filter, or reject an incoming message. A listing is a strong negative signal: it tells the receiving server that mail from this source has caused problems before.

There are more than two hundred blacklists in circulation, but only a small handful carry enough weight to change delivery on their own. This checker focuses on those high-signal lists rather than padding the count with obscure zones that few receivers honor.

How email blacklists work

A blacklist lookup is an ordinary DNS query in disguise. The receiving server reverses your sending IP address, appends the blacklist's zone, and asks for an A record. If the list returns an address in the 127.0.0.0/8 range, you are listed, and the exact return code often encodes the reason for the listing. If the query returns nothing, you are clean on that list. This tool runs the same lookups against every monitored zone at once and reports each answer.

Because the check keys on the IP address, a domain you enter is first resolved to the IP that handles its mail. That is why the result shows both the target you typed and the resolved IP that was actually tested.

Why domains and IP addresses get listed

Most listings trace back to one of a few root causes, and several of them can happen without the owner realizing it.

  • Spam complaints and unsolicited mail. Sending to people who never opted in, or mailing an aged list, drives complaints that blacklist operators act on quickly.
  • Spam traps. Recycled or seeded addresses that should never receive mail are a clear sign of poor list hygiene, and hitting them is one of the fastest routes onto a major list.
  • A compromised account or server. A hacked mailbox, an open relay, or a malware infection can blast spam from your IP, which gets the address listed within hours.
  • Volume spikes and shared IPs. A sudden surge in sending looks like an outbreak, and on shared hosting a neighbor's behavior can pull your address onto a list through no fault of your own.

How to get delisted

Delisting only sticks if you fix the cause first. Requesting removal while the underlying problem is still live almost always leads to a fresh listing, so work through these steps in order.

  1. Confirm which lists you are on. Run the scan above and note every list showing a listed status, along with its return code.
  2. Find the listing reason. Each operator publishes a lookup page that explains why an address was added. Read it before doing anything else so you fix the right thing.
  3. Repair the root cause. Secure or reset any compromised account, close an open relay, clean invalid and unengaged addresses out of your list, and tighten your sending practices.
  4. Request removal, then verify. Submit the operator's delisting request once the problem is resolved. Some lists clear automatically after a quiet period, while others process manual requests within a day or two. Re-scan afterward to confirm the listing is gone.

How to stay off blacklists

Staying clean is mostly about permission and consistency. Mail only people who explicitly opted in, prefer a confirmed opt-in for new subscribers, and remove hard bounces and long-term non-openers on a regular schedule. Keep your complaint rate low, warm new sending IPs gradually instead of blasting them on day one, and publish solid authentication so receivers can tell your mail apart from a spoof. You can verify that authentication with the SPF checker and see how every signal adds up with the sender reputation checker.

A blacklist listing is one signal among several. For a step-by-step walkthrough of removing a listing, read the blacklist removal guide, then run a full reputation check to grade authentication, DNS, and blacklist status together.

Frequently asked

Blacklist questions

What is an email blacklist or DNSBL?
An email blacklist, often called a DNSBL or blocklist, is a database of IP addresses and domains flagged for sending spam or abusive mail. Receiving mail servers query these lists during delivery, and a match counts strongly against your message. Reputation is tracked by sending IP and by domain, not by individual mailboxes, so there is no such thing as a blacklist for a single email address.
How do I check if my domain or IP is blacklisted?
Enter your domain or the IPv4 address of your sending server in the checker above. It resolves a domain to its mail IP, queries every monitored blacklist at once, and shows a clear listed or clean status for each one. For the most accurate read, test the specific IP your mail server uses to send, since that is the address receivers evaluate.
Why did my IP address or domain get blacklisted?
The most common causes are spam complaints from unsolicited mail, hitting spam traps left in an aged list, a compromised account or open relay sending spam from your server, and sudden spikes in volume. On shared hosting or a reassigned IP, you can also be listed because of another sender's past behavior on the same address, which is a false positive you can usually clear with a delisting request.
How do I remove my IP or domain from a blacklist?
First identify every list you appear on and read each operator's explanation for the listing. Fix the root cause, whether that means securing a hacked account, closing an open relay, or cleaning your mailing list, because requesting removal before the problem is resolved leads to a relisting. Then submit the operator's delisting request and re-scan to confirm the listing has cleared.
How long does delisting take?
It varies by operator. Some lists auto-remove low-level listings after a quiet period of a few days, while others process manual requests within 24 to 48 hours once the cause is fixed. Severe or repeat listings, or an address with poor reputation history, can take considerably longer. Even after removal, expect tighter filtering for a while as your reputation recovers.
Do blacklists actually affect email deliverability?
Yes, and the impact depends on which list and how widely it is used. A listing on a high-signal blacklist can cause widespread rejection or spam foldering across Gmail, Yahoo, Microsoft, and corporate filters, while a listing on a niche zone may barely register. Either way, a clean status removes blacklisting as a cause and lets you focus on authentication and reputation.
What is the difference between an IP blacklist and a domain blacklist?
An IP blacklist targets the address of the server sending your mail, so a listing affects every message that leaves that server. A domain blacklist, sometimes called a URIBL, flags a domain name used in the From header or in links inside the message body, so it follows your domain regardless of which IP sends the mail. Many senders monitor both because the two problems have different fixes.
How often should I check my blacklist status?
If you send regularly, check at least once a week, and run an immediate scan whenever you notice a drop in open rates, a rise in bounces, or recipients reporting missing mail. High-volume senders benefit from daily monitoring so a new listing is caught and addressed before it damages deliverability across a full sending cycle.
Which email blacklists matter most?
Out of the hundreds of blacklists in circulation, only a small number meaningfully affect delivery to the major mailbox providers. The widely respected operators that receivers actually honor carry far more weight than the long tail of niche or private lists. A listing on a major list can hurt delivery immediately, while a listing on an obscure one may have almost no effect. This checker focuses on the high-signal lists rather than padding the count.
Should I pay a service to remove me from a blacklist?
No. Legitimate blacklist operators never charge to remove a listing, and any service that offers paid removal from a major list is a scam. Removal is free and is handled directly through the delisting page the operator publishes, once you have fixed the underlying problem. Save your money, repair the root cause, and submit the free request.
Why does my IP keep getting blacklisted?
Repeat listings mean the root cause was never fixed. The usual culprits are a compromised account or server still sending spam, an open relay, poor list hygiene that keeps hitting spam traps, or a shared IP where a neighbor affects you. Delisting without fixing the cause almost always leads to a fresh listing, so secure your accounts, clean your list, and confirm nothing is sending without your knowledge before requesting removal again.
Does one blacklist listing block all my email?
Not necessarily. The impact depends on which list you are on and which receivers honor it. A listing on a major, widely used blacklist can cause immediate rejections or spam placement at large providers, while a listing on a minor list may have little or no effect. Either way, treat any listing as a warning worth investigating, because it usually points to a real sending problem.
Keep exploring

Related tools & resources

Hand-picked next steps for this topic: checkers, guides, and plain-English definitions that go deeper.

Guide Blacklist Removal Guide Check listings, request delisting, and stay off blacklists for good. Term Blacklist (Email) A real-time database of IP addresses or domains known to send spam. Being listed can severely impact email deliverability. Term DNSBL (DNS-based Blackhole List) A blacklist queried via DNS. Mail servers check incoming connections against DNSBLs to identify known spam sources. Tool Reverse DNS Checker Confirm your sending IP has a valid, matching PTR record. Tool Sender Reputation Checker Get a free A to F reputation score across authentication, blacklists, DNS, and infrastructure. Article Why Emails Go to Spam The real reasons messages get filtered, and the fixes that work.