In Outlook, click the File tab in the top left corner. Select Account Settings > Delegate Access.
Click Add button.
Double-click the name of the delegate in the address list, then click OK.
The Delegate Permissions dialog box opens. Assign the desired permissions and click OK.
Click OK again to save and exit out of Delegate Access window.
Back in Outlook, right click a folder you’d like to provide the delegated user permissions for and select Properties.
Under Permissions tab, click Add button.
Same as before, double-click the name of the delegate in the address list, then click OK.
Apple the Permission Level setting and then click OK.
Repeat for any additional folders.