My exchange server is 2000, the clients are a mix of outlook 2000 and outlook 2003. I deleted a user from the exchange server who was previous a delegate on a existing users account (lets call this user1). When a current user schedules an appointment or meeting with user1 the sender receives a Delivery Status Notification (Failure) for the delegate who no longer resides on the system. I cannot location on the workstations or the server where this old user is still located. This only happens within the calendar functions. If you send a message to user1 there are no Delivery Status Notification (Failure).