You can add a domain to account in two ways:
1. as "Alias"
2. as "Additional Domain"
The alias always refers to the root directory of the www server (ie the public_html directory).
The addon domain can refers to any directory on the server (in particular also the server's root directory). By default, adding an additional domain, the system proposes creating a directory with the same name as the domain name, eg by adding the following domain to the account: customerdomain.smarthost.eu domain – customer-domain.eu - it will be installed as an indication to the following directory: customerdomain.smarthost.eu/customer- domain.eu. Of course, the directory pointed to by the addon domain can be changed both during its addition and later in the cPanel panel.
By setting up e-mail accounts in your own domain, both ways of connecting domains do not differ.