Here’s how to check, what to do if you find a listing, and how to prevent it from happening again.
What an Email Blacklist Is and Why It Matters
An email blacklist (also called an email blocklist or DNS blacklist) is a database maintained by anti-spam organisations, internet service providers, or independent operators that lists IP addresses and domains associated with sending spam, malicious activities, or poor email practices. Mail servers query these databases when deciding whether to accept incoming messages – a positive hit can result in messages being rejected, quarantined, or routed to the spam folder.
There are dozens of blocklists in active use, ranging from widely referenced databases like Spamhaus and SORBS to smaller, niche lists maintained by specific email providers. Some domain blacklists focus on sending domains; others focus on the server IP address or sending infrastructure. A listing on a widely used blocklist can affect deliverability across a large proportion of your recipients.
How to Check if Your Domain Is on a Blocklist
Use a Blocklist Checker
The most direct method: run your domain and server IP through a blocklist checker that queries multiple databases simultaneously. Tools like MXToolbox aggregate checks across dozens of blocklists and return a consolidated view of which lists, if any, have flagged your domain or IP address.
To run an ip blacklist check: enter your sending domain or the IP address of your mail server. The tool queries each blocklist database in its index and reports back any hits, along with the specific blacklist’s usage – some are widely respected and affect deliverability significantly; others have limited adoption and minimal practical impact.
Note that some blacklists require payment or an account to access removal request processes – this is normal and not a sign that the blacklist is illegitimate. Check the specific blacklist’s documentation for their removal process before assuming a listing is permanent.
Use Bouncer’s Deliverability Kit for Continuous Monitoring
One-off checks are useful for diagnosing a current problem. For ongoing protection, Bouncer’s Deliverability Kit monitors your sending domain and IP address against major blocklists continuously, sending alerts when a listing is detected. This means you find out about a listing before it affects a live campaign – not after you’ve noticed collapsed open rates and started investigating.
The Deliverability Kit also combines blocklist monitoring with inbox placement testing and authentication verification, giving a complete picture of your deliverability health in one place.
Too Many Spam Complaints: The Most Common Route to Blocklisting
High spam complaint rates are the most common reason a legitimate sender ends up on a blocklist. When enough recipients mark your messages as spam, that signal accumulates across inbox providers and, above certain thresholds, results in blocklist listings or direct filtering decisions.
The threshold varies by blocklist and provider, but Google’s sender guidelines recommend staying below 0.10% complaint rate and treating 0.30% as a ceiling. Above that level, deliverability problems follow quickly.
Reducing spam complaints requires sending relevant content to contacts who genuinely want it, maintaining a clear and functional unsubscribe link in every email, and not sending to contacts who haven’t engaged in an extended period. Email Engagement Insights helps identify which contacts are still active – protecting you from sending to abandoned inboxes where messages pile up unreceived and eventually generate spam complaints when the account is checked or closed.
Other Common Causes of Blocklist Listings
- Spam trap hits – sending to addresses maintained by anti-spam organisations to identify senders with poor list practices. Bouncer’s Toxicity Check reduces this risk through probabilistic scoring.
- Sending spam emails or malicious content – either deliberately or because your email infrastructure has been compromised. If your mail server or email account is sending spam without your knowledge (a compromised server, a hijacked account), you can end up on a realtime blacklist rapidly. Monitor your sending logs for unusual activity.
- Malware and phishing links in messages – either inserted by malicious actors who have compromised your sending infrastructure or present in content from third-party sources you’ve incorporated into your emails. Blocklist operators that focus on malicious content list domains that serve or distribute malware and phishing links, regardless of whether the domain owner was aware.
- Spammy websites linked from your email domain – if your website domain is associated with malware, phishing, or other malicious activities, that association can affect your email domain’s standing with blocklist operators who monitor web reputation alongside email behaviour.
How to Request Removal From a Blocklist
If you find a listing, the process is:
- Identify the root cause before requesting removal. A removal request without fixing the underlying issue will result in a re-listing quickly. Audit your list for spam trap indicators, check your spam complaint rate, verify your authentication is correct, and confirm your sending infrastructure hasn’t been compromised.
- Follow the specific blacklist’s removal process. Each blocklist has its own procedure – some are automated (submit a removal request online, wait for propagation), some require a manual review and explanation of what changed, some involve a waiting period after the underlying issue is resolved.
- Monitor after removal. Use Bouncer’s Deliverability Kit to confirm the listing is removed and that deliverability has recovered. If complaint rates or trap hits continue, a re-listing will follow quickly.
Most legitimate senders who end up on a blocklist due to list hygiene issues can achieve removal within days to weeks, provided the root cause is genuinely addressed. The more tools you have monitoring the situation continuously, the faster you catch and resolve issues before they require a formal removal process.
FAQ
How do I query if a domain is on a whitelist or blacklist?
To figure out your domain status, you need to check it against a blacklist database. These databases are maintained by isps and security providers to track domains or IPs associated with spam, viruses, or suspicious behavior.
The easiest way is to use a blacklist checker. You enter your domain or sending IP, and the tool runs an email blacklist check across multiple sources. This helps you determine whether your domain is listed and which such blacklists are affecting you.
There isn’t really a universal “whitelist” you can query in the same way, but if your domain consistently sends clean traffic and aligns with best practices, most systems will treat it as trusted and allow your emails to be delivered properly.
How to check if a domain is blacklisted / blocked
Start with a multi-source scan. A good blacklist checker will search across dozens of lists at once, including major industry databases used by isps and email server providers.
You should check both your domain and your IP. Sometimes your domain is fine, but your sending infrastructure is blocked at the IP level.
Beyond that, review your technical setup. Make sure your spf record is configured correctly, because misconfigurations can trigger filtering or listings. Also look at your sending patterns–sudden spikes, poor list quality, or spam complaints can all lead to being flagged.
Some tools offer free scans, while others provide deeper diagnostics and ongoing monitoring with additional support. If your business relies heavily on email marketing, ongoing checks are worth it.
Our domain is probably blacklisted – how to find out where?
If you suspect an issue, the first step is to run a full email blacklist check using a tool that aggregates results from multiple blacklist database sources. This will show exactly where your domain or IP appears and help you determine the scope of the problem.
Next, look at the context. Listings often come from poor data in your email lists, sending to suspicious or invalid contacts, or patterns that resemble spam. In some cases, unrelated issues like compromised systems or even harmful backlinks on your site can contribute to trust problems.
Once you know where you’re listed, follow each provider’s removal process. Most such blacklists have clear steps for delisting, often requiring you to fix the root cause before they review your request.
For any serious company relying on email, this should not be a one-time fix. Regular monitoring, clean data practices, and proper infrastructure help you avoid future listings–and keep your emails consistently delivered instead of filtered or blocked.
