A website can be added to security blocklists if it is suspected of distributing malware, sending spam, hosting phishing pages, or exhibiting other harmful behavior. Browsers, search engines, email providers, and security companies use these lists to protect users from potentially unsafe websites.
If your website has been blacklisted, visitors may see security warnings, search engines may reduce its visibility, or some services may refuse to connect to it. Checking your website’s reputation can help determine whether a blacklist is affecting its availability.
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Common signs that a website may be blacklisted
The following symptoms can indicate that your website has been flagged by one or more services:
- Visitors see warnings in their browser before accessing the site.
- Search engines display security notices next to search results.
- Emails sent from the domain are rejected or marked as spam.
- Antivirus software blocks access to the website.
- External services refuse to connect to the domain.
These symptoms do not always mean that your website has been blacklisted, but they are often the first indication that further investigation is needed.
Check your website with online reputation tools
Several public services allow you to check whether your domain appears on security or spam blocklists. Most of them only require you to enter your domain name.
You can use tools such as:
- Google Safe Browsing Transparency Report, which checks whether Google has flagged your website as unsafe.
- VirusTotal, which compares your website against dozens of security vendors and reputation databases.
- Sucuri SiteCheck, which scans websites for malware, blacklisting, and security issues.
- MXToolbox Blacklist Check, which checks whether your domain or mail server appears on common email blocklists.
- Spamhaus Lookup, which allows you to verify whether your domain or IP address has been listed for spam-related activity.
Different services maintain different databases, so a website may appear on one list but not another.
Check for browser warnings
Open your website in a private or incognito window and look for messages such as:
- “Deceptive site ahead.”
- “This site may harm your computer.”
- “The connection is not private.”
- Security warnings displayed by antivirus software.
If possible, test the website from another device or network to confirm that the warning is not caused by local browser settings or extensions.
Review your website for signs of compromise
Blacklisting is often caused by unauthorized changes to the website.
Check whether:
- Unknown files or folders have appeared.
- New administrator accounts have been created.
- Plugins or themes have been modified unexpectedly.
- The website redirects visitors to other pages.
- Spam pages have been added to the site.
If you use a content management system such as WordPress, make sure that the core software, plugins, and themes are up to date.
Check your email reputation separately
Website reputation and email reputation are not always linked. A domain can have a healthy website while its emails are blocked, or the opposite.
If the problem affects email delivery, you may also need to verify:
- SPF, DKIM, and DMARC records.
- Mail server reputation.
- Email-specific blocklists.
Tools such as MXToolbox and Spamhaus Lookup can help you investigate email-related reputation issues.
What to do if your website is blacklisted
The first step is to identify why the website was flagged. In many cases, the blacklist entry will include additional information about the suspected issue.
After resolving the underlying problem, some providers allow you to request a review or removal. Depending on the service, this process can take anywhere from a few hours to several days.
Removing a website from a blacklist without addressing the original cause may result in the website being flagged again.
What to expect
Not all blacklists work in the same way. Some are updated automatically, while others require manual review. It is also possible for different security providers to reach different conclusions about the same website.
If you suspect that your website has been blacklisted, checking multiple reputation services can help determine whether the issue affects browsers, search engines, email delivery, or another part of your online presence.