Good Afternoon, Here is my situation.....I installed a second Exch 5.5 server in my site, moved all mailboxes, public folders, address books , etc. to the new server. Installed the IMC on the new server, but had it relay all outgoing email through the IMC on the first server. Works fine. I am now ready to retire my old exchange server. However, when I change the IMC so it is using DNS to send outgoing email instead of relaying through the first server, the queue fills up with undeliverable messages, host unreachable. To fix it I have to change it back so that it is relaying through the first server again. Any idea why? ********************* Scott Overfield Network Administrator Gratiot County Community Mental Health (989)466-4109 *********************