IP Blacklist Checker

Check whether an IP address is on anti-spam blacklists (RBL/DNSBL) in real time.

Checking... 0 / 0
Target IP:

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Lists containing IP: 0 (clean)
Total Scanned
0
Clean
0
Listed
0
Errors
0
Blacklist / DNSBL Provider Status Return Code Details / Delist Information Latency Action

About IP Blacklist Checker

The IP Blacklist Checker tests whether an IPv4 address is listed in real-time anti-spam DNS blacklists (DNSBL / RBL). Major email service providers and firewalls consult these lists to reject spam and malicious traffic.

By reversing your IP octets and querying authoritative DNSBL zones (such as Spamhaus, SpamCop, Barracuda, SORBS, and Abuseat), this tool provides an instant health check of your mail server, VPS, or public IP reputation.

Key features

  • Multi-RBL Coverage Queries over 30 leading DNSBL and RBL databases simultaneously, including Spamhaus ZEN, SpamCop, Barracuda Central, SORBS, and UCEPROTECT.
  • Real-Time Concurrent Lookups Dispatches parallel asynchronous DNS checks with live progress updates, allowing full verification in just seconds.
  • Return Code & TXT Record Diagnostics Analyzes return codes (such as 127.0.0.2 for spam or 127.255.255.x for open resolver refusals) and retrieves TXT records containing delisting instructions.
  • Filtering & Export Capabilities Instantly filter results by listed, clean, or error status, with one-click export to CSV and formatted clipboard copy.

How to Check an IP on Blacklists

Follow these steps to diagnose email deliverability and IP reputation issues.

  1. Enter the IPv4 address Type the public IPv4 address of your mail server or host (e.g., 8.8.8.8), or click "Use My IP" to test your current connection.
  2. Initiate the blacklist check Click the "Check" button to launch parallel DNS queries against all monitored DNSBL databases.
  3. Review the summary score Observe the "Lists containing IP" indicator. A clean IP will display "0 (clean)" with a green badge.
  4. Inspect detailed listing reasons and delist links If listed on any RBL, filter by "Listed" to inspect the specific return code, TXT message, and click the direct link to the provider's removal page.

Usage tips

  • Always test the outbound mail server IP (from email headers or SPF records) rather than your personal home IP when diagnosing delivery failures.
  • Spamhaus and Barracuda may return lookup errors or query refused codes (127.255.255.254) when queried via public DNS resolvers like Google DNS or Cloudflare.
  • Before submitting a delisting request, ensure open relays, malware infections, and spam scripts on your server have been completely eradicated.
  • Periodic automated monitoring helps identify compromised servers before significant reputation damage occurs.

Frequently asked questions

A DNSBL (DNS-based Blackhole List) or RBL (Real-time Blackhole List) is a real-time database published via DNS containing IP addresses known for sending spam, hosting malware, or operating open relays. Mail servers query these lists to reject unwanted incoming emails.
The checker reverses the four octets of the target IPv4 address and appends the DNSBL zone domain (e.g., 8.8.8.8 becomes 8.8.8.8.zen.spamhaus.org). A response in the 127.0.0.0/8 range indicates the IP is listed, whereas NXDOMAIN (no record) means it is clean.
A lookup error typically indicates that the DNS query timed out or the DNSBL provider refused the query. For instance, Spamhaus and Barracuda restrict queries from public open resolvers (such as 8.8.8.8 or 1.1.1.1) and require dedicated registration for high volume queries.
First, examine your mail logs and system processes to identify and eliminate the source of spam, insecure passwords, or misconfigured relays. Then, visit the delisting link provided in the results table to submit an unblock request.
Not necessarily. Each email receiving provider (like Gmail, Outlook, Yahoo) configures its own spam scoring rules. Tier 1 lists like Spamhaus ZEN and SpamCop have a major impact, while smaller lists may only contribute a fractional spam score.