If your emails are being rejected, websites are blocking you, or you're seeing CAPTCHAs everywhere, your IP address might be blacklisted. Here's what that means and how to fix it.
What Is an IP Blacklist?
An IP blacklist (also called a DNSBL or blocklist) is a database of IP addresses that have been flagged for suspicious or malicious activity. Email servers, websites, and security services check these lists to block spam, hacking attempts, and other abuse.
Major blacklists include:
- Spamhaus — the most widely used email blacklist
- Barracuda — used by businesses for spam filtering
- SORBS — Spam and Open Relay Blocking System
- SpamCop — real-time spam reporting
- CBL — Composite Blocking List
Why Your IP Might Be Blacklisted
Common reasons your IP ends up on a blacklist:
- Spam emails — your device or network was used to send spam (possibly by malware)
- Malware infection — a virus on your device is sending spam or attacking other systems
- Shared IP — another user on the same IP (common with dynamic/shared IPs) did something malicious
- Open relay — your email server was misconfigured to relay spam
- Previous owner — the IP was previously assigned to someone who abused it
- VPN/proxy IP — VPN server IPs are frequently blacklisted due to abuse by other users
How to Check If You're Blacklisted
Follow these steps:
- First, find your IP address at CheckWhatIsMyIP.com
- Visit MXToolbox.com/blacklists.aspx — it checks 100+ blacklists at once
- Enter your IP address and click "Blacklist Check"
- Review the results — green means clean, red means blacklisted
You can also check individual blacklists:
- Spamhaus: check.spamhaus.org
- Barracuda: barracudacentral.org/lookups
- SpamCop: spamcop.net/bl.shtml
How to Get Delisted
Step 1: Fix the Root Cause
Before requesting removal, fix whatever caused the blacklisting:
- Run a malware scan on all devices on your network
- Check for compromised email accounts
- Secure your email server (if applicable)
- Change passwords on affected accounts
Step 2: Request Removal
Most blacklists have a removal/delisting process:
- Spamhaus: Visit their removal center and follow the self-service process
- Barracuda: Submit a removal request on their website
- Time-based: Some blacklists automatically remove IPs after a period of no further abuse
Step 3: Change Your IP
If delisting takes too long, you can try to get a new IP address:
- Restart your router (may assign a new dynamic IP)
- Contact your ISP to request a new IP
- Use a VPN to bypass the blacklisted IP entirely
How to Prevent Future Blacklisting
- Keep all devices updated and run antivirus software
- Use strong, unique passwords for all accounts
- Monitor your network for unusual outbound traffic
- Use email authentication (SPF, DKIM, DMARC) if you run a mail server
- Regularly check your IP against blacklists
Stay on top of your IP's reputation by checking it regularly with our IP Lookup Tool.