Blacklist Check
Mail bouncing or landing in spam? Check whether the sending IP or domain is flagged on 14 major blacklists.
Checks 14 blacklists. Domains resolve to their mail server (or A record) first.
Related: look up where that IP is located.
This check is sent via DNS-over-HTTPS to Cloudflare, with Google and NextDNS as fallbacks.
Learn about email blacklists
How a blacklist check actually works
DNSBLs (DNS-based blocklists) publish their data as a special DNS zone. To check an IP, a reversed version of it is queried as a subdomain of the blocklist's own zone. Getting back a result means the address is listed. No result means it's clean. This tool checks the IP or domain against 14 major blacklists that way. If you enter a domain instead of an IP, it resolves through the domain's mail server (or its A record) first.
Reading your results
Being listed on one small or obscure blacklist rarely affects deliverability much. Being listed on a handful of major ones is a real problem worth fixing. Listings usually come from one of a few causes: sharing a hosting IP with another sender who's spamming, a compromised account or server sending outbound spam, a missing reverse DNS (PTR) record, or the sender genuinely sending unsolicited mail.
Common questions
I'm listed. What do I do? Find that specific blacklist's own delisting process, usually a form on their site, and fix the underlying cause first. Requesting removal before the real problem is resolved just means getting listed again shortly after.
Why does this show a different result than my email provider's own monitor? Some blacklists respond differently to automated bulk queries than they do to a provider's monitored feed, and listings can change within minutes, so two checks a short time apart can genuinely disagree.
Does a clean result guarantee my email won't land in spam? No. Blacklist status is one deliverability factor among several. SPF, DKIM, and DMARC configuration, sending reputation, and message content all matter too.