Each Mailbox can have a Class attribute. This attribute specifies the type of the information this Mailbox is created for: Calendar, Contacts, Tasks, Notes, etc. If a Mailbox does not contain the Class attribute, it means that it is created to store regular E-mail messages.
The Mailbox Class does not restrict the types of data that can be stored in the Mailbox: E-mail and Contacts messages can be stored in Mailboxes with the Tasks Class, Notes messages can be stored in Calendar Class Mailboxes, etc. The Mailbox Class information is used with the advanced user interfaces (WebUser, MAPI) to present the Mailbox content in the proper format.
When a Mailbox is created with an advanced client interface, the interface can set the Mailbox Class. Mailbox Classes can also be updated using the CommuniGate Pro CLI/API.