I rebooted my Exchange 2003 server this morning and then received a number of complaints as staff were both sending and receiving emails and NDR's dated from July last year. Upon investigation it also appears that some of these emails/NDR's had already been received yet some had not.
In the end I had to go into the Queues Section of Exchange and delete all the NDR's as there were over 600 still to be processed.
It is a fairly simple set up, we have an Direct SMTP connection that does not go through Messagelabs (or similar) and no secondary route (that I am aware of).
Any ideas why the reboot caused this influx of messages and why they did not come through/Go out in the first place.