I wonder if i can separate Mail, DNS on 1 server rather than putting everything on 1 server(IIS). It's just simply not cost effective at all by doing that.
I'm using another control panel product and it allows me install DNS, Mail or Mysql/MSSQL on 1 server and only need to install the control panel on the IIS server. All IIS servers share the same dns, mail, SQL server.
Yes, you can install separate services on different servers - Helm is designed to support a multi-server environment. So you can have the control panel on one server with IIS, and DNS on another, mail on another, etc.