SBS 2008sp2 with Exchange 2007 (build 08.01.0340.000). All PC's are XPpro running Office 2007.
Background - Original SBS2003 server failed some time ago. IT rep at that time installed this new SBS2008 server and migrated/imported Exchange Users into Exchnage 2007. All existing Domain/Exchange user accounts worked ok. OWA is enabled and availble to all users from internet or internal.
Problem - Created new domain user account in ADUC and created Exchange mailbox. Setup user on PC and configured Outlook to use Exchange account. Outlook connects to Exchange and will send/receive mail. Every few minutes a login window pops up saying "Connect to OWA.<domainname>.com" and Outlook shows "Needs Password". (See Attachment). I have also tried creating a new domain/exchange user using the SBS Management Console with identical results.
Have tried entering username, username@<domainname>.com,
l all using domain password with no success. Have tested OWA by going to HTTPS://owa
.<domainname>.com/owa using domain username/password successfully. Compared new user domain and Exchange mailbox settings against existing working users and they appear identical.
Original IT rep that installed new server had same issue. He apparently demoted PC from domain to workgroup, configured Outlook to Exchange, and had user login to Outlook/Exchange at PC login as a workaround. This apparently stopped the OWA login pop up but left PC out of domain.