Based on the facts presented in this article, here are some possible scenarios and conclusions:
Choose Schema version 2 native mode for both Calendar Server and Messaging Server products at configuration time.
If you have an existing two DIT LDAP structure with a DC tree, and you don't want to migrate to a single DIT structure, you can choose Schema version 2 compatibility mode.
You must have Access Manager installed in legacy mode in order to use Delegated Administrator.
Install Access Manager in legacy mode to enable Delegated Administrator. Choose Schema version 2 native mode for both Calendar Server and Messaging Server products at configuration time. Delegated Administrator creates Access Manager-ready LDAP records, but you are not required to implement any other Access Manager features.
Choose Schema version 2 native mode. Migrate your existing LDAP database to Schema version 2 mode. Use Delegated Administrator interfaces to administer domains, users and groups.
Choose Schema version 2 compatibility mode for both calendar and messaging applications.
You can choose to keep all Communications Suite products in Schema version 1 mode, but administration of two products in Schema version 1 mode will be difficult and involve many different interfaces, some of which are deprecated.
For further information on migrating your old Schema version 1 mode system to Schema version 2 mode, see Sun Java Communications Suite 5 Schema Migration Guide.