> CA certificate signing is orthogonal to encryption. Yes in the broad sense and no in the specific case. In order to activate macOS Mail encryption you need

> CA certificate signing is orthogonal to encryption. Yes in the broad sense and no in the specific case. In order to activate macOS Mail encryption you need a certificate on your keychain. So by having a CA issue you a certificate, the mail client can generate the keys to encrypt that mail without additional passwords (e.g., relying on in-situ authentication). So in this application they are interrelated.