Free tool

Blacklist / RBL Checker

Enter a domain or IP address to check it against 10 well-known DNS-based email blacklists, the same public DNS zones every blacklist checker queries under the hood. Useful when outbound mail is landing in spam and you need to know whether your sending IP is the reason.

For a domain, we check its mail server's IP (via MX record), the address that actually sends your email and the one blacklists care about. Checks 10 well-known DNS-based blacklists (Spamhaus, SpamCop, SORBS, and others) directly, in parallel.

By using this tool, you agree to our Terms of Service , only run it against something you own or are authorized to assess.

Go deeper

DNS Security Basics: SPF, DKIM, and DMARC Explained Business Email Compromise: How These Attacks Actually Work Microsoft 365 service Consulting service

Listed and not sure why?

Getting delisted is only half the fix, we help track down and close the actual gap that got a mail server blacklisted in the first place.

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