A delegate automatically receives Send on Behalf permissions. By default, the delegate can read only your meeting requests and responses. The delegate isn’t granted permission to read other messages in your Inbox.
The delegate must be a person in your organization's Exchange Global Address List (GAL).
Open Outlook.
Click the File tab.
Click Account Settings and then click Delegate Access.
Click Add...
Type the name of the person whom you want to designate as your delegate or search for them and then click their name in the results list.
Click Add then click OK.
In the Delegate Permissions dialog box, accept the default permission settings or select custom access levels for Exchange folders. If a delegate needs permission to work only with meeting requests and responses, the default permission settings, such as Delegate receives copies of meeting-related messages sent to me, are sufficient. You can leave the Inbox permission setting at None. Meeting requests and responses will go directly to the delegate’s Inbox.
By default, the delegate is granted Editor (can read, create, and modify items) permission to your Calendar folder. When the delegate responds to a meeting on your behalf, it is automatically added to your Calendar folder.
To send a message to notify the delegate of the changed permissions, select the Automatically send a message to delegate summarizing these permissions check box.
If you want, select the Delegate can see my private items check box.
This setting affects all Exchange folders. This includes all Mail, Contacts, Calendar, Tasks, Notes, and Journal folders. There is no way to grant access to private items in only specified folder
Click OK.
NOTES:
Messages sent with Send on Behalf permissions include both the delegate's name and your name next to From. When a message is sent with Send As permissions, only your name appears.
Once you add someone as a delegate, they can add your mailbox to their Outlook profile. For instructions, see Manage another person's mail and calendar items.
What are the Delegate Permission Levels?
Reviewer
With this permission, the delegate can read items in your folders.
Author
With this permission, the delegate can read and create items, and change and delete items that he or she creates. For example, a delegate can create task requests and meeting requests directly in your Task or Calendar folder and then send the item on your behalf.
Editor
With this permission, the delegate can do everything that an Author has permission to do and additionally can change and delete the items that you created.