- Plesk Onyx for Linux
Using Let's Encrypt provided certificate The Bat! mail client in not able to establish encrypted connection using S/MIME.
An error occurs:
This S/MIME certificate is invalid for signing on behalf of email@example.com
Let's Encrypt certificate does not provide S/MIME certificates for mail securing.
Using Let's Encrypt certificate there is only standard TLS encryption available while mail sending/receiving.
This task is pure administrative.
- Purchase S/MIME certificate from an authoritative organization (e.g Comodo, Enthrust, Trustwave, etc) and set it for mail encryption.
- Use S/MIME compatible mail client.