Acrobat shows an unacceptable signature banner? Install the Signattio trust root once

Acrobat and Adobe Reader verify signatures against the Adobe Approved Trust List (AATL) and the European Commission's EU Trusted Lists. A certificate that is not on either list gets the open question, not a green tick — the software is saying: I found a valid signature, now tell me whether you vouch for the issuer.

The Signattio signing root lives in your own domain, not Adobe's, so the banner is the honest default. The signature itself is already complete: signer identity and document digest, plus an RFC 3161 timestamp token when an authority is configured. Only the trust link between your reader and our root is missing.

Windows and macOS Reader both ship the same trust flow:

1. Open the signed PDF and open the signature panel in the left sidebar.

2. Click Signature Details (or right-click the signature field) and open the Certificate tab in the dialog.

3. At the top of the chain, the self-signed root is at the root of the issuer chain (marked "(untrusted)"). Select it and click Add to Trusted Certificates.

4. In the trust dialog, tick Use this certificate as a trusted root and Certified documents; save.

5. Reopen the document: the signature panel now shows the green check mark.

Alternative path without a signed document open: Edit > Preferences (Reader)/Acrobat [Great] > Signatures > Identities & Trusted Certificates > Import. Same certificate, same trust anchor.

macOS validates signatures with its own chain engine:

1. Ask the document's author (the envelope sender) for the root certificate file (.pem or .crt) if they have not shared it.

2. Open Keychain Access, pick the System keychain, and drag the certificate file in.

3. Double-click the imported certificate, expand Trust, and mark it Always Trust for X.509 policy.

4. Close the window and confirm the system password. Preview and other Mac readers validate through the system trust chain from this state.

Every Signattio envelope carries its own evidence pack: the audit-trail chain hash, signer identity method, signature appearances and a hidden immutable evidence certificate. The reader's banner is about its own trust stores only; the package's evidence is independent of how your reader is set up.

To check a document without installing anything, open the verification page embedded in the delivery email — the verification code is also printed inside the evidence certificate.

The baseline profiles cover routine business flows only when the level actually reached supports them; check the PAdES level recorded in your evidence pack. If your legal team needs a qualified signature, use a qualified trust service provider; this service provides an advanced signature with evidence, not a qualified one.