Each platform user has an Account created inside the CommuniGate Pro Server user database. The Account name looks like userName@domainName, and it becomes the user's E-mail, Calendar, SIP, and XMPP address.
Each Account (such as email@example.com) belongs to some Domain (company.dom in this case). CommuniGate Pro Server supports multiple Domains, each with its own independent set of Accounts, Groups, Aliases, and other Objects, its own set of Default Account settings, own set of E-mail and Signal Rules, own security Certificates, etc
A Domain can have its own dedicated IP address(es), or several Domains can share the same IP address(es).
When the platform is used for hosting, each Domain can be administered remotely by Domain Administrators - Accounts in that Domain with administrative rights granted to them.