You are not allowed to send this message because you are trying to send on behalf of another sender without permission to do so. Please verify that you are sending on behalf of the correct sender, or ask your system administrator to help you get the required permission.
Diagnostic information for administrators:
2.Delete the offline address book folders in
Windows 7: C:\Users\username\AppData\Local\Microsoft\Outlook\Offline Address Books
Windows XP: C:\Documents and Settings\username\Local Settings\Application Data\Microsoft\Outlook\Offline Address Books
3.Open Outlook and let it download a new copy of the offline address book.
3.1 Send/Receive Tab
3.2. Send/Reveive Groups
3.3 Download Address Book
3.4 Choose Full Details and \Global Address List