Are you with Proton? Maybe the documentation you need is just a lock on the sent email that says "Used key for <email> from keys.openpgp.org", and the recipient

Are you with Proton? Maybe the documentation you need is just a lock on the sent email that says "Used key for <email> from keys.openpgp.org", and the recipient could also have a cleartext message saying "Encrypted with key for <email> from keys.openpgp.org"?