I have a windows 2000 server running exchange 2000 as a front-end server and I have 3 identical servers running as back-end servers. Everything has been working great and then out of nowhere mail that we received from external sources started showing up in users mailboxes 30 minutes late. The remote delivery queues for the 3 back-end servers stay consistantly at around 100 messages in the queues. Mail delivery has not stopped, but damn it sure is slow. We have not made any changes or installed any updates. I am running SP4 on windows 2000 and SP3 on Exchange 2000. Does anyone have any idea why this is happening?