How to Remove "On Behalf Of" in Outlook
In the Microsoft Outlook application, you can grant other users access to your email account using the delegates feature. When a delegate sends a message from your account, the words "On Behalf Of" appear at the top of each outgoing email. To get rid of this and make it appear like the account's owner is sending the message, a server administrator must manually grant the delegate "Send As" permissions.
Log on to your PC server with an administrative username and password.
Open the "Start" menu, go to the "Programs" list, expand the "Administrative Tools" folder and click on "Active Directory Users and Computers."
Go to the "View" menu at the top of the window and check the "Advanced Features" option.
Double-click on the username for which you want to set up sending permissions.
Go to the "Security" tab at the top of the pop-up window.
Press the "Add" button and enter the username of the individual for whom you want to be able to send messages without the "On Behalf Of" text.
Check the "Allow" box for the property labeled "Send As." Make sure none of the other property boxes are checked.
Click "OK" to save the settings.