Files to update :
- /etc/dovecot/conf.d/10-ssl.conf
- /etc/postfix/vmail_ssl.map => postconf -F vmail_ssl.map
- /etc/postfix/helo_access
- /etc/postfix/sender_access
To generate the certs :
certbot certonly apache -d asite.com -d www.asite.com -d mail.asite.com
Add PTR record