Free blacklist check tool for IPs and domains

Blacklist check overview:

  • A blacklist check shows whether your sending IP or domain is listed on public email blacklists that can cause bounces and Spam/Junk placement.
  • Regular blacklist checks help you quickly confirm whether deliverability issues are driven by sender reputation.
  • Sendmarc’s free blacklist checker gives you a clear, shareable view of which blacklists (if any) list your IP or domain.

A blacklist check tool shows whether your IP address or domain appears on email blacklists that harm deliverability. If your emails are bouncing, landing in Spam or Junk, or performing worse than expected, a quick check can confirm whether your sender reputation is the problem.

Sendmarc’s free blacklist checker scans your IP or domain against email blacklists and gives you clear insights that you can share with your IT, email, or security team.

Enter IP or domain → Select Lookup → Review your blacklist status.

Overview of a blacklist check

Sendmarc Blacklist Lookup Tool

A blacklist check is a scan that looks up your IP address or domain on email blacklists. These blacklists are anti-spam databases that mailbox providers use to identify and block suspicious or abusive senders.

When you run a check in our blacklist lookup tool, you see whether your IP or domain appears on commonly used public blacklists and exactly which ones list it. That insight turns a vague deliverability issue into a clear sender reputation problem that you can investigate and fix.

A blacklist check is an essential step in troubleshooting issues such as sudden bounce spikes, Spam and Junk folder placement, or unexpected drops in engagement.

Why a blacklist check matters for email deliverability

Mailbox providers use both content and reputation signals to decide where to place your email. If your IP or domain is blacklisted, your messages are more likely to go to Spam/Junk or be rejected entirely. Even strong content and clean design can’t overcome a poor reputation.

Regular blacklist checks help you:

  • Confirm whether reputation is contributing to deliverability issues
  • Investigate sudden changes in delivery or engagement

For security teams, a blacklist checker is also a useful early-warning tool. An unexpected listing can point to a compromised system, account, or integration that’s sending unwanted or malicious email on your behalf.

Run a check

How to use our blacklist checker tool

Sendmarc’s blacklist checker is designed to be simple to use.

You start by entering the IP address or domain that sends your email into the search field. After you select Blacklist Lookup, the tool queries public blacklists and returns the results. This shows which blacklists, if any, list your IP or domain.

From there, you can:

  1. Share the results with your internal teams
  2. Use the information to guide deeper technical investigation

Many teams use this blacklist lookup tool as a standard step whenever a campaign underperforms or users report missing emails.

What to do if your blacklist check shows a listing

If your blacklist check shows that your IP or domain is listed, it’s important to respond in a structured way.

Start by confirming that the listed IP or domain is still sending email. If it is, review recent changes. List growth, new campaigns, or third-party tools can all play a role.

Next, address likely root causes. Improve list hygiene by removing unengaged or unknown contacts, reviewing how people were added to your lists and whether you have clear consent to email them, and investigating any signs of account or system compromise. Once you’re confident that risky behavior has been corrected, you can begin the delisting process.

Every blacklist has its own process. Some provide forms, others accept requests by email, and certain lists remove entries automatically after a period of clean sending. After delisting, it’s good practice to run regular blacklist checks to confirm that your reputation remains stable.

Using Sendmarc’s blacklist check with DMARC

A single blacklist check gives you a snapshot of your current status. When you combine that snapshot with Domain-based Message Authentication, Reporting, and Conformance (DMARC) data, you gain a much deeper view of your email environment.

With Sendmarc, you can use blacklist results alongside DMARC reports to see who’s sending email on behalf of your domain and identify risky sources that are causing blacklisting.

Secure your sender reputation with Sendmarc

Manual blacklist checks are helpful, but they only tell you what’s happening at a specific moment. If your business relies on email, you need ongoing visibility into both reputation and authentication.

Sendmarc provides automated monitoring of blacklisted sources, continuous DMARC enforcement, and clear reporting, so you can see issues early and take action before customers are affected.

Learn more about how we monitor blacklist sources and authentication, and protect your sender reputation around the clock.

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Blacklist check FAQs

What is a blacklist check?

A blacklist check is a scan that looks up your IP address or domain on email blacklists, which are anti-spam databases used by mailbox providers to identify risky senders. A blacklist check helps you understand whether your sender reputation is contributing to deliverability issues.

A blacklist check works by taking the IP address or domain you use for sending email and querying it against known public anti-spam blacklists. The blacklist check then returns a list of blacklists where your IP or domain appears, which helps you investigate and resolve reputation problems.

If your blacklist check shows that you’re on multiple blacklists, the blacklist check is signaling a serious issue with your sending behavior. You should first fix the underlying cause, then follow the removal process for each blacklist.