uncomment and chagne SSL keys pointing in /etc/dovecot.conf
change /etc/dovecot/dovecot.conf
point SSL certificates in dovecot to same place as postfix certs, or after update dovecot ssl stops working
change
ssl_cert_file = /etc/ssl/.my-domain.tld/.my-domain.tld.crt
ssl_key_file = /etc/ssl/.my-domain.tld/.my-domain.tld.key
to smtpd_tls_cert_file = /etc/postfix/smtpd.cert smtpd_tls_key_file = /etc/postfix/smtpd.key