Domain Blacklist Checker

An email blocklist (or DNSBL — Domain Name System Blackhole List) is a real-time database of IP addresses and domains flagged for sending spam. Major email providers like Gmail and Microsoft query these lists when deciding whether to deliver your mail.

Not all listings are equal

There are hundreds of blocklists and most are irrelevant. A listing on a major list like Spamhaus genuinely affects delivery. A listing on an obscure list most providers ignore may need no action at all. This tool separates the two so you know which findings matter.

How do you get blocklisted?

• Spam Traps: Sending emails to hidden addresses created by anti-spam organizations specifically to catch bulk mailers.
• High Complaint Rates: When too many recipients click the “Mark as Spam” button in their inbox.
• Compromised Servers: If your server is hacked and used to send malware or phishing links.
• Shared IP Neighbourhood: If you are on a shared hosting plan, you might be listed because another customer on the same IP is sending spam.

What to do if you are listed on a major blocklist

Stop sending immediately. Continuing to send while listed on a list like Spamhaus deepens the damage. Identify why you were listed — a purchased list, a missing DMARC record, a compromised server — and fix the underlying cause before requesting delisting. Never request delisting before fixing the problem, or the list operator may refuse to delist you again.

A listing only on a minor list is worth understanding, but it is rarely the reason your email is going to spam. Check the other two factors first: why authenticated emails still land in spam.