Domain Blacklist Check
Verify whether your domain is listed on major DNS-based blacklists (DNSBLs). A blacklisted domain can result in email delivery failures, reduced search engine rankings, and blocked web traffic. A free tool by IPv4Center.
What Is a Domain Blacklist?
A domain blacklist (also called a DNS-based Blackhole List or DNSBL) is a database of domain names that have been associated with spam, malware, phishing, or other malicious activities. Email servers and security systems query these lists to decide whether to accept or reject messages from a domain. Being listed on a blacklist can severely impact your email deliverability and online reputation. For IP-level checks, use our blacklist check tool.
Why Should You Check Your Domain?
Regularly checking your domain against blacklists helps you maintain a healthy sender reputation. If your domain is blacklisted, emails sent from your domain may be rejected or marked as spam by recipient mail servers. Early detection allows you to take corrective action — such as removing malware, fixing open relays, or requesting delisting — before significant damage occurs. See our blacklist removal guide for step-by-step instructions.
How DNS-Based Blacklists (DNSBLs) Work
A DNS-based Blacklist (DNSBL) is a real-time database queried via the Domain Name System that lists IP addresses and domains associated with spam or malicious activity. The lookup mechanism works by reversing the octets of an IP address and appending the blacklist zone name — for example, checking 192.0.2.1 against zen.spamhaus.org results in a DNS query for 1.2.0.192.zen.spamhaus.org. A positive response (typically 127.0.0.x) indicates a listing.
Major blacklist providers include Spamhaus (maintaining the SBL, XBL, PBL, and DBL lists), Barracuda Central (BRBL), SpamCop (BL), SORBS, and UCEPROTECT. Each provider uses different criteria and data sources — Spamhaus relies on spam traps, manual investigations, and automated detection; Barracuda uses its global email traffic data from millions of endpoints.
URI-based blacklists like Spamhaus DBL and SURBL specifically target domain names found in email body content rather than sender IPs. Mail Transfer Agents (MTAs) check both the connecting IP against IP-based DNSBLs and any URLs in the message body against URI-based lists, creating a multi-layered filtering system.
Common Causes of Domain Blacklisting
Spam transmission is the leading cause of domain blacklisting, whether from intentional bulk unsolicited email or compromised accounts sending spam without the owner's knowledge. A single compromised email account can generate thousands of spam messages within hours, triggering automated blacklist entries across multiple providers.
Malware distribution and phishing campaigns cause immediate blacklisting with severe consequences. If a domain is used to host malware payloads, serve phishing pages, or act as a command-and-control server, it will appear on security-focused blacklists like Spamhaus DBL, Google Safe Browsing, and PhishTank within minutes of detection.
Open mail relays and misconfigured SMTP servers remain a persistent cause of blacklisting. When a server accepts and forwards email from unauthenticated sources, spammers exploit it as a relay point, causing the server's IP and associated domain to be listed. Similarly, missing or incorrect SPF, DKIM, and DMARC records increase the likelihood of being flagged by recipient systems.
Frequently Asked Questions
A domain blacklist check resolves your domain to its IP address, then queries multiple DNS-based blacklists (DNSBLs) to see if that IP is listed. Each blacklist maintains its own database of IPs associated with spam or abuse. A positive response indicates the IP is listed.
First, identify the cause — common reasons include compromised servers, spam activity, or shared hosting with a bad neighbor. Fix the underlying issue, then visit each blacklist's website to submit a delisting request. Most blacklists have automated delisting processes that take 24-48 hours.
This tool checks your domain against major DNSBLs including Spamhaus ZEN, SpamCop, Barracuda Central, SORBS, UCEPROTECT, PSBL, and CBL (Composite Blocking List). These are the most widely used blacklists by email servers worldwide.
It's recommended to check your domain at least weekly, or more frequently if you send high volumes of email. Consider using automated monitoring to get instant alerts when your domain or IP is listed on a blacklist.
Yes. In shared hosting environments, multiple domains share the same IP address. If any domain on that server sends spam or is compromised, the shared IP can be blacklisted, affecting all domains on it. This is called "bad neighbor" effect. Using a dedicated IP or VPS mitigates this risk.
IP blacklisting blocks traffic based on the sender's IP address, while domain blacklisting blocks based on the domain name itself (often checked via URI-based blacklists like SURBL or Spamhaus DBL). Both can affect email delivery. This tool resolves your domain to its IP and checks IP-based blacklists.