ZI² Books
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Is your domain certified?
Enter a domain. We read its public DNS and report whether it publishes a ZI² Certified server key, alongside its SPF, DKIM and DMARC records.
01
What the check reads
Four public records, straight from DNS. The lookup runs in your browser. The domain you type never reaches us.
_zi2cert
Server key
The Ed25519 public key that proves which machine sends your mail.
TXT
SPF
Which addresses may send for the domain.
_domainkey
DKIM
Whether message content is signed.
_dmarc
DMARC
What a receiver should do when a check fails.
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Certified domains
32 domains publish a ZI² Certified server key today. To find out whether a particular domain is one of them, run the check above. We do not publish the list.