Free tool · No account
Blacklist Checker — Spamhaus, SpamCop, Barracuda & more.
Bounces just spiked and you suspect a listing. A single blocklist hit can quietly tank your inbox rate at the providers that respect it. Check your sending IP or domain against every major DNSBL at once, with a direct link to request removal from any that flag you.
- 6 major blocklists checked
- Domain or IP accepted
- Free, no account
Enter a domain or a sending IP address. We resolve domains to their A record automatically, then check against 6 major DNS-based blocklists in parallel.
How this works
Blocklists, in plain English.
How does a DNSBL lookup actually work?
Each blocklist publishes a DNS zone. To check an IP, you reverse its octets and query "<reversed-ip>.<zone>" for an A record — if one comes back, the IP is listed. It's the same mechanism every major mail server uses internally, just exposed here as a simple form.
I'm listed. Now what?
Fix the underlying cause first — usually a spam trap hit, a compromised account sending abuse, or a shared IP poisoned by another tenant — then use the removal link for that specific blocklist. Requesting removal before fixing the cause just gets you re-listed.
Why do I show clean here but still land in spam?
DNSBLs are one signal among many. Gmail, Outlook and Yahoo weigh engagement, content, SPF, DKIM and DMARC, and their own private scoring of your domain far more heavily than public blocklists for everyday filtering decisions — a clean check here doesn't guarantee inbox placement.
Which blocklists actually matter?
Spamhaus and SpamCop are the two most widely respected across mailbox providers and spam filters. Barracuda and Mailspike matter mainly for recipients running that vendor's own security appliance. UCEPROTECT and SORBS are more aggressive and have higher false-positive rates — a listing there is worth investigating but less urgent.
Emails in spam right now?
Find out why in the next two minutes.
Paste the headers of one email that landed in spam. You get the reason Gmail or Outlook filed it there, and the first thing to fix.