File: //usr/share/webmin/virtual-server/help/config_default_domain_ssl.html
<header>Setup SSL certificate from provider for hostname?</header>
When enabled, Virtualmin will try to automatically set up a valid SSL
certificate with the default SSL provider for the hostname during the next
configuration check.<p>
If successful, this SSL certificate will be used as the fallback for all
services that do not have their own SSL certificate configured. <p>
If the system's hostname changes, it will be automatically detected and updated
upon configuration check.