Perform the following steps:
Choose Tools -> Settings.
Click Delegation for Exchange in the left pane.
In the Delegating to Others tabbed section, select the delegate whose permissions you want to modify, then click Edit.
On the Permissions for username dialog, select the permissions for the delegate for your Calendar, Contacts, Inbox, and Tasks folders. Select the role for the delegate from the drop-down list beside each folder. A set of permissions is associated with each role. For example, if you select the Author role, the delegate can read the contents of the folder and add items to the folder.
Select the Delegate can see private items option to enable the delegate to view appointments, meetings, and tasks whose Classification is Private.
Click OK on the Permissions for username dialog.
Click OK on the Settings dialog.