- Plesk Onyx for Linux
- It is not possible to login to any mail client with the following error message:
CONFIG_TEXT: Unable to establish a secure SSL connection to example.com
- The certificate for mail server was renewed recently.
- Let's Encrypt is configured to issue ECDSA certificates in
key-algorithm = ECDSA
ecdsa-curve-name = prime256v1
- ECDSA certificate is used to secure mail server at Tools & Settings > SSL/TLS certificates> Certificate for securing mail
This is Plesk bug #PPPM-10356 which will be fixed in future Plesk versions.
As a workaround, do not use ECDSA certificate for securing mail server.