Log a better error message if ssl_cert_file doesn't point to a valid certificate.
Log a better error message if ssl_cert_file doesn't point to a valid certificate.

LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot,LTD-Beget/dovecot