The wedge
Every verification comes with a receipt.
Anyone can verify it.
ZeroBounce says an email is valid. NeverBounce says it's not. Which one do you show your client? Your compliance team? The auditor? Today, you just trust the vendor's dashboard. That's the problem ZI² Certified solves.
ZI² Certified
Signed. Public. Provable.
A verdict is an opinion. A signed receipt is evidence anyone can audit.
The mechanism
How it works
You verify an email.
The engine runs MX + SPF + DMARC + syntax + disposable + role-account + catch-all + SMTP probing. Same accuracy as ZeroBounce, NeverBounce, Kickbox.
The result is signed.
An Ed25519 signature covers the exact checks that ran, when, against what MX server, and with what score. Tampering with any part breaks the signature.
The public key is on the open internet.
Our JWKS lives at verify.zi2.app/.well-known/zi2cert.jwks. You don't have to trust us. You can verify our signature yourself, in any language, in 20 lines of code.
Anyone can prove your result was real.
Paste any receipt into /verify-receipt — no account, no login, no API call to us. Signature valid → we tell you exactly what checks ran and when. Signature invalid → you know somebody edited the receipt.
Anatomy of a receipt
Every field is covered by the signature.
The checks that ran, the MX they ran against, the score, the timestamp, the key id — all sealed under one Ed25519 signature. Change a single character and verification fails.
Read the receipt format{
"email": "[email protected]",
"verdict": "deliverable",
"score": 94,
"checks": {
"mx": true,
"spf": "pass",
"dmarc": "found",
"disposable": false,
"role": false,
"catch_all": false
},
"mx_host": "aspmx.l.google.com",
"checked_at": "2026-07-30T14:02:11Z",
"kid": "v1",
"sig": "MEUCIQD8f…q2b7Xn0A"
} Who it's for
Why this matters to your buyer
SDR / RevOps
Prove to your VP that the list you handed off was actually verified — not "trust me, I ran ZeroBounce."
Deliverability lead
Show ISPs (Gmail postmaster, Outlook SNDS) that the addresses you sent to had documented, signed verification.
Compliance / DPO
Auditable proof for GDPR + CAN-SPAM: you had legitimate interest to verify, and you can show what you did, when.
Agency selling to a client
Give the client a receipt they can independently verify. Removes the "did you actually run this?" doubt from every invoice.
No signup required
Try it now — no signup
Paste any ZI² Certified receipt into our public verifier. It runs entirely in your browser — the signature check never leaves your machine.