is there a way for a customer using virtualmin to create the one the extra web sites that he need by creating a new virtualmin host and not the system administrator
such an option in virtualmin is not available for the moment but cpanel and plesk have such an option
A sub-server is a virtual server owned by an existing virtual server (domain) account, assuming you’ve allowed your domain owners to create sub-servers. A sub-server can have all the same features as a top-level virtual server, including mail, databases, apps, etc. The only difference is in ownership (it’s owned by the top-level server) and location (it lives in the domains subdir of the owning domain account).