Free Blocklist Checker for IPs and Domains:
Review Your Reputation
Emails bouncing or landing in Spam or Junk? A blocklisted IP or domain is often the reason. Sendmarc’s blocklist checker scans your IP or domain against public email blocklists and shows exactly which ones list it, so you can confirm whether reputation is the problem.
Enter your IP address or domain to check its blocklist status.
What Is a Blocklist Checker?
A blocklist checker looks up an IP address or domain against public email blocklists: real-time databases that mailbox providers use to identify and block suspicious or abusive senders.
IT and email administrators use it to confirm whether a listing explains a delivery problem. Security teams use it as an early-warning check for a compromised system or account sending unwanted email. Marketing teams use it to rule out a reputation issue when a campaign underperforms.
IP address · 192.0.2.10
Listed on 1 of 4 blocklistsWhy Blocklist Checks Matter
Mailbox providers weigh both content and reputation signals when deciding where to place a message. If your IP or domain is on a blocklist, messages are more likely to land in Spam or Junk, or get rejected outright. Strong content and clean design don’t matter if reputation is the problem.
A blocklist check replaces guessing with a clear answer: whether reputation is behind the issue, and which list is responsible if it is.
Common Use Cases
- Delivery troubleshootingConfirm whether reputation is behind sudden bounces or Spam folder placement
- Security investigationSpot a compromised system or account before it does more damage, since an unexpected listing can point to an unauthorized sender
- Campaign checksRule reputation in or out whenever a campaign underperforms
What Sendmarc’s Blocklist Checker
Shows You
Enter an IP address or domain and get a clear view across public blocklists.
Blocklist status
Whether the IP or domain appears on commonly used public blocklists
Listing detail
Exactly which blocklists list it, if any
192.0.2.10
How to Use Sendmarc’s Blocklist Checker
- Enter your IP or domain.Type the sending IP address or domain into the search field.
- Select Blocklist Lookup.The tool queries public blocklists and returns the results.
- Review the result.See which blocklists, if any, list your IP or domain.
- Act on it.Share the result with your team, or use it as the starting point for a deeper investigation.
Run a blocklist check any time a campaign underperforms, or delivery looks off, rather than guessing at the cause.
What to Do If Your Blocklist Check Shows a Listing
Start by confirming whether the listed IP or domain is still sending email.
Next, address the likely root cause.
Every blocklist has its own process.
Using Sendmarc’s Blocklist Monitoring with DMARC
A manual check only tells you what’s happening at one moment. Sendmarc pairs automated blocklist monitoring with continuous DMARC enforcement and clear reporting, so issues surface early instead of after customers are affected.
See how Sendmarc combines blocklist monitoring with DMARC enforcement to protect your reputation on an ongoing basis.
Book a demoBlocklist Checker FAQs
What is a blocklist check?
A blocklist check is a scan that looks up your IP address or domain on email blocklists, real-time databases mailbox providers use to identify suspicious senders.
How does a blocklist check work?
A blocklist check queries the IP address or domain you send from against known public blocklists and returns which ones, if any, list it.
What should I do if I’m on multiple blocklists?
Being on multiple blocklists signals an underlying reputation issue. Fix the root cause first, then follow each blocklist’s own removal process.
How long does it take to get removed from a blocklist?
It depends on the blocklist. Some remove listings automatically after a period of clean sending; others require a manual delisting request, and turnaround time varies by provider.
Does a blocklist check affect whether my emails get delivered?
No. Running a check doesn’t change anything. It only reveals whether an existing blocklisting is affecting delivery, so you can act on the underlying cause.
How often should I run a blocklist check?
Run a check whenever you see a spike in bounces, a drop in engagement, or a delivery issue you can’t otherwise explain, and periodically after resolving a listing to confirm your reputation has stabilized.