Free tool
Blacklist checker.
Even perfect SPF, DKIM, and DMARC will not save you if your sending IP is already listed on a DNS-based blacklist (DNSBL). Enter a domain to check its inbound mail server (MX) IP, or paste the IP you actually send from, against Spamhaus ZEN, SpamCop, and Barracuda.
Run the check
We resolve the IP
A server-side MX lookup for your domain’s inbound mail server — or the IP you paste. Outbound mail can leave from other IPs, so paste your sending IP to check it. No signup, nothing stored.
We query three DNSBLs
Spamhaus ZEN, SpamCop, and Barracuda — the blacklists most receivers actually consult.
You get a clear verdict
Listed on any of the three is a fail — receivers reject or spam-folder that IP regardless of SPF/DKIM/DMARC. A query that fails or is refused shows as inconclusive, never as clean.
Other free checks
SPF checker
Look up and grade your SPF record — policy strength, multiple-record errors, and DNS-lookup limits.
DMARC checker
Check your DMARC policy, enforcement level, and reporting — the records Gmail and Yahoo now require for bulk senders.
Spam-word checker
Scan a subject line and body for common spam-trigger phrases like "act now" and "100% free" before you send.
CogniLead runs on a warmed sender pool with a reputation circuit-breaker that pauses a domain before it ever reaches a blacklist. You bring the leads.