Before you add an archiving task, ensure that the Enterprise Vault system mailbox is available. See the Installing and Configuring manual for instructions.
To add an Exchange Mailbox archiving task
In the left pane of the Administration Console, expand the Enterprise Vault site hierarchy until the Enterprise Vault Servers container is visible.
Expand the name of the computer on which you want to create an archiving task.
Right-click Tasks and, on the shortcut menu, click New and then Exchange Mailbox Task.
If an Exchange Provisioning task does not exist for the domain, then one will be created automatically.