Email Blacklist Checker

Getting blacklisted is one of the most damaging things that can happen to your email program. When your domain or IP appears on a major blacklist like Spamhaus, your delivery rate can drop from 95% to near zero overnight. This checker scans multiple blacklist databases simultaneously so you can catch listings early—before they crater your entire campaign performance.

How email blacklists work

Email blacklists (also called DNSBLs or RBLs) are real-time databases of IP addresses and domains that have been flagged for sending spam. When a mail server receives your email, it checks the sending IP and domain against these lists before deciding whether to accept, filter, or reject the message. The lookup happens via DNS, which makes it extremely fast—a mail server can check dozens of blacklists in milliseconds. Different blacklists have different listing criteria and impact. Spamhaus is the most widely used and a listing there can block delivery to over 3 billion mailboxes worldwide. Smaller lists like SORBS or UCEPROTECT have less reach but can still affect delivery to specific providers.

Why you might be blacklisted (and how to fix it)

The most common cause is high spam complaint rates—if more than 0.1% of your recipients mark your emails as spam, you're in dangerous territory. Other triggers include sending to spam traps (email addresses specifically created to catch spammers), high bounce rates from sending to unverified lists, and compromised accounts sending spam without your knowledge. To fix a listing, you need to identify and resolve the root cause first. Clean your list with our email validator, remove anyone who hasn't engaged in 6+ months, and make sure your SPF and DKIM authentication is properly configured. Only then submit a delisting request—if you request removal without fixing the problem, you'll get listed again within days.

The blacklists that actually matter

Not all blacklists are equal. Spamhaus operates several lists (SBL for known spam sources, XBL for exploited systems, PBL for dynamic IPs) and is checked by the majority of mail servers worldwide. Barracuda maintains a widely-used list that many corporate email systems rely on. SpamCop tracks spam reports from individual users. CBL (Composite Blocking List) focuses on IPs sending spam from bots and malware. A listing on Spamhaus or Barracuda is an emergency—drop everything and fix it. A listing on a smaller, less-used list is concerning but not catastrophic. This checker shows you which specific lists you're on so you can prioritize your response.

Preventing future blacklist listings

Prevention is far easier than recovery. Run every new subscriber through an email validator at signup and reject disposable addresses. Implement double opt-in to confirm subscriber intent. Monitor your bounce rate weekly—keep it under 2%. Watch spam complaint rates in Gmail Postmaster Tools and aim for under 0.05%. If you're warming up a new domain, follow a gradual schedule using our warmup calculator rather than blasting your full list on day one. Set up automated monitoring that alerts you if your domain or IP appears on any blacklist so you can respond before delivery drops significantly.