Grant Send on Behalf of Permissions on a mailbox in Exchange 2010

This guide shows you how to grant send on behalf permissions on a mailbox:

• Open up the Exchange Management Console.
• Expand Recipient Configuration.
• Click Mailbox.
• On the right hand side double click the mailbox you want to modify.

• Step 1 -> Right click on the user account.
• Step 2 -> Click on Properties.

• Step 1 -> Click on the Mail Flow Settings Tab.
• Step 2 -> Click on Delivery Options.
• Step 3 -> Click on Properties.

• Click the Add button to select a user.

• Select the user or group from the list and then click on OK.

• Once you have selected the user it will show as above.
• Click OK.
• Back at the main mailbox properties window, click apply and ok.

Hope it helps.