Blacklist Check

IP Blacklist (DNSBL) Lookup Guide

If your emails are suddenly bouncing or being marked as spam, your mail server’s IP address may be listed on a blocklist. This tool queries 7 major DNS-based Blockhole Lists (DNSBLs).

Supported Inputs

• IPv4 Address: e.g., 192.168.1.1

How to Interpret the Output

• The tool queries 7 specific zones (like zen.spamhaus.org, b.barracudacentral.org, etc.).
• A result of Listed means the blocklist has flagged this IP.
• A result of Clean means the IP is not present on that specific list.

Realistic Example

If you query a known spam IP on zen.spamhaus.org:

• The tool will return a response (often 127.0.0.x), confirming the IP is listed.
• You must then visit the specific list’s website to request delisting.

Common Errors & Limitations

• Not a guarantee: Being clean on these 7 lists does not mean you aren’t listed on hundreds of other global or private blocklists (like Microsoft or Google’s internal lists).
• IPv4 Only: This implementation currently focuses on IPv4 addresses.