We have a few options available for branding / whitelabeling the service.
For our regular, non-reseller customers, you can take two different paths to branding.
Crossbox branding is not necessarily an alternate choice from the mail/webmail/mailadmin subdomains pointing to your primary server. However, they are two separate things. We recommend that you at least use the “mail” subdomain pointing to the primary mail server, and have “webmail” or any other subdomain you like point to Crossbox. Crossbox is a different product, sitting on a different server, that uses your primary mail server as it’s back-end.