IP Reputation & Blacklist
Scan your IP address against the most trusted RBL and DNSBL providers to identify potential listing issues.
Mail Deliverability
If your mail server's IP is listed on an RBL, your emails may be automatically rejected or marked as spam by major providers like Gmail or Outlook.
Inbound Security
Use this tool to verify if a visiting IP address is known for malicious activities, helping you decide whether to block or challenge the traffic.
Data Cleaning
Validate your user database or log files by checking IP reputations. Identify automated bots and potential abusers early.
What is an IP Blacklist?
An IP blacklist (also known as a DNSBL or RBL) is a real-time database that identifies IP addresses associated with spam, malware, and other malicious activities. These lists are used by mail servers and security systems to filter traffic and block communication from known high-risk sources.
Understanding DNSBL and RBL
DNS-based Blackhole Lists (DNSBL) and Real-time Blackhole Lists (RBL) work by publishing a list of addresses as DNS records. This allows server-side software to perform a quick lookup and decide whether to accept or reject a connection based on the sender's reputation.
How Listings Happen
- • Spam Traps: Sending mail to unmonitored "trap" addresses.
- • Open Relays: Misconfigured servers that allow anyone to send mail.
- • Malware: Infection on the server causing automated attacks.
- • Dynamic IPs: Some lists block entire residential IP ranges by default.
Best Practices
- • Check Regularly: Reputation can change based on network neighborhood.
- • Monitor Logs: Look for SMTP 550 errors referring to specific RBLs.
- • Reverse DNS: Ensure your IP has a valid PTR record matching your hostname.
- • Delisting: Follow official provider links to request manual removal.
FAQ: IP Reputation
Is being listed on an RBL permanent?
No. Most listings are temporary. Once the malicious activity stops (e.g., you fix your mail server), many lists will automatically drop your IP after 24-72 hours. Others require a manual request.
What is the "127.0.0.x" response?
DNSBLs return loopback addresses to indicate why an IP is listed. For example, Spamhaus ZEN returns 127.0.0.4 for an exploited device and 127.0.0.10/11 for dynamic IPs.
Does this check IPv6?
Currently, most standard RBLs focused on IPv4. While IPv6 blacklisting is emerging, this tool primarily targets the IPv4 ecosystem where reputation tracking is most mature.
Will this tool block my IP?
No. This is a lookup-only tool. It queries third-party databases to provide you with visibility into how the rest of the internet views your IP address.