Function Copy SSL Certificate to Dovecot in Manage SSL Certificate copies the certificate files to the server's root folder (/):
Copying certificate and key to Dovecot files ..
.. wrote out certificate and CA in /dovecot.cert.pem, and key in /dovecot.key.pem
Enabling SSL in Dovecot configuration ..
But this should be for example to /etc/dovecot.
Also no certificate for the CA is copied, but it should be for example to:
Also the entry:
ssl_ca = = </etc/dovecot/dovecot.ca.pem
should be added to: