Every time I have to re boot the mail server after installing software updates to the server. I end up with the system sending out undeliverable messages to most of the staff in the office. This can be from months ago. However every time I check the smtp queues there are never any messages awaiting to be delivered. Has anyone any suggestion as to what is happening here. Where are these massages hiding? Regards Neville

What NDR are you getting? Also, what does message tracking have to say on the NDR's? If its not enabled, here's how: http://www.msexchange.org/tutorials/The_Exchange_Message_Tracking_Center_or_How_to_Save_Your_A_in_a_Pinch.html