I have some strange behavior in one domain. We have Windows 2000 forest with lot of domains. In that particular domain they had installed Exchange 5.5 on Windows 2000 member server. Almost everything is OK with one exception. No user has access to their mailbox when they are placed in normal Domain Users group. When they try access mailboxes repeatedly Outlook logon dialog appear and even they put in correct logon credentials they got warning that their logon information was incorrect. But if I place user to the Domain Admins group he/she can access his/her mailbox without problem. Strange, isnt it? Any ideas? Thank you...MCE