It is a good time to move to Exchange 2003. With the end of Microsoft's support of this release within 2003 they have to decide to move to a new release of Exchange Server. In this article I will talk about detailed overview on how to migrate an Exchange 5.5 directory to a new Windows Server 2003 supported Exchange Server 2003 environment. The main issue with the migration from Exchange Server 5.5 to 2003 is to move the Exchange directory service to Active Directory from the old Windows NT 4.0 structure. Because Exchange Server 2003 new features are fully supported on Windows Server 2003 it is best to run this combination although you can run several combinations. In general there are just two main ways for moving to Exchange Server 2003. The first is to upgrade an existing Exchange 5.5 environment by running an inplace upgrade which is not recommend for many reasons. Another way is to migrate the Exchange directory service to Active Directory and then implementing an Exchange Server 2003 environment. Just so you know the compatibilities of Exchange on top of Windows I will mention a few combinations that are supported by Microsoft. Exchange 5.5 will work with Windows NT and Windows 200. Microsoft Exchange 200 will work with Windows 2000 and can be supported in a Windows 2003 active directory. Exchange 2003 can be run on a Windows 2000 service pack 3 and Windows 2003 machine. Until recently Exchange could only be run on Windows 2003. When you are ready to perform the migration to exchange you must prepare the active directory connector. Install the Active Directory Connector from your Exchange Server 2003 CD in your environment. Then you have to configure the appropriate connection agreements for public and private folders. The account that has to be specified for running the Active Directory Connector should have service account permissions. The import and export process has to be configured using accounts that have the appropriate permissions to read and write to the specified directories. The configuration connection agreement is configured automatically and will make sure that Exchange Server 5.5 directory service will synchronize the complete configuration with Active Directory Services. Once you are successful with the ADC you can then begin the process of moving the mailboxes Before you can start the Move Mailbox Procedure using Exchange Deployment Tools or ?Active Directory Users and Computers? you should check whether there is a one-to-one relationship between your Accounts and Mailboxes. An easy way to check this automatically is to use the Ntdsattrb.exe tool that can be found on your Exchange Server 2003 CD, too. Once you have moved the mailboxes you should got to a workstation and test by opening outlook. If everything looks ok then move the mx record and continue moving all mailboxes. That's it. Well almost. There a few other network things and database preparation but for the most part this is how to migration from Exchange 5.5 to Exchange 2003