I have recently installed an SBS 2008 server and joined the clients to the new domain. Since doing this a message box appears when the users start Outlook saying, 'connecting to remote.<our domain name>', the box then keeps popping up periodically as long as Oulook is open.
More network detail:
Previously, the site had a basic workgroup, I used the Files and Transfer settings wizard to move data between their workgroup login and their new domain login. Users used to connect to pop3 accounts for mail, but now mail is routed to the server and the old pop3 accounts serve as backup acounts should the primary route not be available. The server is an SBS 2008 standard server and the clients are all XP pro running office 2003.