Hi all, I would really appreciate if some one guide me of his experience. The scenario is as follows... Current Environment. I have two domains, one of Windows NT 4.0 (Name "COMM") having only one server (Name "MAIL"), which is PDC and MS Exchange 5.5 (with service pack 4) running on it, all the mail users has their account on this server and there is no on-line folder BUT Outlook web access is configured and some users has some data residing in their folders/mailboxes. The second domain is of Windows 2000 server and Active Directory is installed on it. All users get authentication from this domain (Name ADSD) The users accounts on both these servers are different, for example, Mr. Jhon Smith has a user account "jhon.smith" on "COMM" domain and has user name "jhon" on "ADSD" domain. Not all of the accounts are different but about 40% accounts are different on both domains. Requirement. Now I have a spare server and I want to finish "COMM" domain and upgrade of MS Exchange 5.5 server to MS Exchange 2000 server with full integration with Active Directory WITHOUT LOSING ANY INFORMATION /DATA residing in the mailboxes of different users. I would really appreciate if some body has experience of this scenario and share with me. Thanks, Arshi Jamal