Try this command, replace <mail.domain.tld> to your domain.
/root/.acme.sh/acme.sh --issue -d <mail.domain.tld> --cert-file /etc/letsencrypt/live/<mail.domain.tld>/cert.pem --key-file /etc/letsencrypt/live/<mail.domain.tld>/privkey.pem --fullchain-file /etc/letsencrypt/live/<mail.domain.tld>/fullchain.pem -w /usr/local/lsws/Example/html --force --debug
After successfully generate new ssl with above command and ‘cert’ still expired at checktls.com use the command below as su -.
postmap -F hash:/etc/postfix/vmail_ssl.map
systemctl restart postfix
systemctl restart dovecot