To provision a domain and to learn about creating a hosted domain entry in the organizational tree for Sun Java System LDAP Schema v.1, refer to Chapter 2, Provisioning Domains, in the iPlanet Messaging Server 5.2 Provisioning Guide
For information on how to customize the mail client interface for each domain, refer to Chapter 8, Customizing Communications Express for a Specific Domain, in the Sun Java System Communications Express Customization Guide