Delivery assurance
See which prepared document was sent, where it was sent, and the delivery result reported by the fax network. The certificate helps detect changes to that record; it does not confirm someone read or accepted the document.
The technical details
The certificate identifies the prepared PDF submitted for delivery, including any cover, reference footer, or image processing—not just its filename or the original upload. If even one byte changes, the fingerprint no longer matches. The fax network may alter the received image.
CourierSeal retains the transmission identity, destination endpoint result, and verified callback evidence used to build the delivery record.
An Ed25519 signature binds the document fingerprint and delivery facts. Verification uses CourierSeal’s independently published public-key registry.
When configured and verified, an RFC 3161 authority timestamps the signature. CourierSeal validates the signer pin, policy, imprint, nonce, and certificate purpose—not merely the token’s presence.
Revision-safe evidence
Late verified delivery evidence never silently rewrites a previously issued certificate. CourierSeal retains linked revisions so an investigator can distinguish what was known at each issuance.
The assurance boundary
A verified certificate supports that the recorded PDF fingerprint and delivery facts have not changed since CourierSeal signed them, and—when timestamp verification succeeds—that an approved authority anchored the signature in time. It records the destination fax endpoint’s final network result.
It does not prove that a particular person read, understood, or legally accepted the document, nor that every fax-network hop was end-to-end encrypted. Legal effect depends on applicable law and surrounding evidence.
