Blacklist Checker

What Are DNS Blacklists?

DNS Blacklists (DNSBLs), also called Real-time Blackhole Lists (RBLs), are databases of IP addresses known to send spam or malicious email. Email servers query these lists when receiving messages to decide whether to accept, reject, or flag incoming mail. If your mail server's IP appears on a blacklist, your emails may be blocked or sent to spam folders.

How Blacklists Work

When someone sends you an email, your mail server can perform a DNS lookup against one or more blacklists. The lookup checks whether the sending server's IP address is listed. If found, the receiving server applies its configured policy—rejecting the message outright, adding spam points, or quarantining the email for review.

Blacklists compile their data from various sources:

• Spam traps: Email addresses that should never receive legitimate mail
• User reports: Complaints submitted to blacklist operators
• Honeypots: Servers designed to attract and identify spammers
• Automated detection: Pattern analysis of known spam campaigns

Getting Delisted

If your IP lands on a blacklist, take these steps:

1. Identify the problem: Determine why you were listed. Common causes include compromised accounts, misconfigured servers, or being on a shared IP with a spammer.
2. Fix the root cause: Remove malware, secure compromised accounts, or implement proper authentication (SPF, DKIM, DMARC).
3. Request removal: Most blacklists offer a self-service delisting process. Some remove IPs automatically after a period of good behaviour.
4. Monitor continuously: Check your IP regularly to catch new listings quickly.

What We Check

Our blacklist checker queries major DNSBLs to see if your mail server IPs are listed. We check popular lists including Spamhaus, Barracuda, and others that email providers commonly use. Regular monitoring helps you maintain good email deliverability and catch problems before they impact your communications.