You can better understand GroupWise if you understand the terms used within the architecture.
Administration and Management is responsible for directory and system administration tools to maintain the GroupWise Address Book and configuration information about your GroupWise installation.
The message store system is a series of post offices on the network. It securely houses your information in the form of calendars, messages, documents, indexes, and folders.
The message transfer system is composed of message transfer agents (MTAs) which route messages between the post offices, gateways, and directory agents.
The client provides the user interface to the services in GroupWise.
Third-party interfaces consist of GroupWise implementations of industry standard APIs and GroupWise-specific APIs to support developers who extend the functionality of your GroupWise system.