Hi, SSL Certificate is not issued for hosted subdomains, ex: mail.domain.com How do I issue SSL Certificate for mail.domain.com in order to use the subdomain (mail.domain.com as host) in mail application with SSL. Thank you!
Are you talking about the ssl certificate for postfix and dovecot e.g. smtp and imap/pop service? The certificate should automatically be setup during the installation of ISPConfig and should be the hostname you specified for the host before installing ISPConfig. Is this a new system? Can you share which guide you followed?
Such a cert should not be issued as subdomains of the email domain are not used to access mail services. As @pyte mentioned, only the system hostname is used to access mail services, and an SSL cert is created for the system hostname at install time. If you do not remember your system hostname, you can see it when you run the command: hostname -f on the shell of your server. I recommend reading the email getting started guide to learn how to configure an email client to connect to your ISPConfig mail server: https://www.howtoforge.com/ispconfig-email-account/
