I could not use the function "out of office assistant" from tool menu in outlook2000. Could anyone tell me how I change the setting of Exchange 5.5 so that I can use "out of office assistant" in office?

Use outlook web access to set the out of office assistant.. Since the exchange server is a "Server centric" email system. It wants these rules to run on the server. This way outlook doesnt have to be open for the out of office reply to reply. If you go in through OWA, it will give you the option for out of office assistant and when set will create a server side rule that will run whenever an email comes into the inbox and the Outlook clients doesnt need to be open.