DNSBL Blacklist Check

What is a DNSBL email blacklist?

A DNSBL (DNS-based Blackhole List) is a special DNS zone that contains IP addresses known or suspected to send spam, malware or other unwanted traffic. When a mail server receives a connection, it can run a DNSBL blacklist check to decide whether to accept, reject or flag an incoming email.

Popular email blacklist providers include Spamhaus, Spamcop, Barracuda, SORBS and others. Each DNSBL maintains its own criteria for listing and delisting IP addresses, usually based on spam reports, spam traps or suspicious sending behavior.

Why should you check your IP reputation?

If your mail server IP address appears on one or more DNSBLs, your messages may be rejected, delayed or delivered directly to the spam folder. Running a regular email blacklist check helps you:

• Understand why emails are not delivered or end up in spam
• Detect hacked or misconfigured servers that send unsolicited mail
• Monitor your IP reputation over time
• Verify that a new mail server is clean before going live

How this DNSBL blacklist check works

This tool takes your domain or IPv4 address, resolves it to an IP address and then performs lookups against several popular DNSBLs. For each blacklist it shows whether the IP is listed and, if available, additional details from the DNSBL provider. This gives you a quick overview of your current blacklist status without installing any software on your system.