Planning to Move from Exchange 5.5 to Exchange 2003


Topic Last Modified: 2005-10-25

If your current organization is running Exchange 5.5, you have two options for moving to Exchange 2003, the standard path and the external migration path. These are explained in "Deployment Options" below.

There is no option for performing an in-place upgrade from Exchange 5.5 to Exchange 2003. This means that you cannot upgrade an Exchange 5.5 server to Exchange 2003. To upgrade your organization from Exchange 5.5 to Exchange 2003, you will instead install an Exchange 2003 server on separate hardware and connect it to your existing Exchange 5.5 organization using Active Directory Connectors.

You must have a stable Active Directory® directory service environment before you deploy Exchange 2003. You will use the Exchange version of Active Directory Connector (ADC) to maintain coexistence between organizations until you have moved all of your users and data to Active Directory and Exchange 2003.

You do not necessarily have to be completely finished with your Active Directory deployment before you deploy Exchange 2003. For example, you may not be ready to move all Microsoft Windows NT® accounts to Active Directory, but you may want to define an Active Directory domain that can host Exchange 2003 mailboxes. In this case, you can allow ADC to create placeholders in Active Directory for the Windows NT accounts. Exchange 2003 uses these placeholders to ensure e-mail functionality with Exchange 5.5 sites that are not deployed in an Active Directory domain. Then you can move the mailboxes for these accounts to Exchange 2003 servers that are deployed in an Active Directory domain. When you are ready to join the Windows NT accounts to Active Directory (either by upgrading the Windows NT domain or using Active Directory migration tools), you can merge the mailbox placeholder with the Windows account.

Depending on your situation, you can select one of two paths to move from Exchange 5.5 to Exchange 2003:

  • Standard path (recommended)   Deploy Exchange 2003 in the Exchange 5.5 organization.

  • External migration path   Migrate Exchange 5.5 data to a separate Exchange 2003 organization.

Regardless of your current environment, the recommended deployment path is the standard path, which involves installing Exchange 2003 into an existing Exchange 5.5 organization. By following this path, you can use the new Exchange Server Deployment Tools in Exchange 2003, which contain all of the recommended steps, diagnostic tools, and setup links that help you install Exchange 2003.

If you cannot install Exchange 2003 into your existing Exchange 5.5 organization, your other choice is to migrate Exchange 5.5 data to a separate Exchange 2003 organization.

This method is recommended because you can take advantage of the Exchange Server Deployment Tools that lead you through the entire process. The Exchange Server Deployment Tools provide the recommended steps, diagnostic tools, and setup links to help you successfully install Exchange 2003.

This strategy is optimal for your organization if you do not plan to make major architectural or topological changes. You should already have Active Directory deployed within your organization, but it is not necessary to upgrade all of your Microsoft Windows NT Server version 4.0 domains or user accounts to Windows 2000 Server or Windows Server 2003. Each Exchange 5.5 site must contain at least one server running Exchange 5.5 with SP3. It is also recommended that your existing organization contain at least one Active Directory domain that is in native mode.

With this method, you run the Deployment Tools which take you step by step through the installation. This includes:

  • Installing ADC

  • Using ADC Tools to set up connection agreements that synchronize Exchange 5.5 directory information with Active Directory.

  • Connecting new server hardware that is running Exchange 2003 to your existing Exchange 5.5 organization.

  • Moving mailboxes and replicate public folders from Exchange 5.5 to your new Exchange 2003 server.

The following resources contain complete information about using the standard migration path method to deploy Exchange 2003:

An alternative to adding a new Exchange 2003 server to the Exchange 5.5 organization involves creating a separate Exchange 2003 organization and migrating directory information and mailboxes from the 5.5 organization to the new Exchange 2003 organization. This method requires that Active Directory be in place in the target organization. If accounts are in a separate forest from the mailboxes, you must establish a trust between the two forests to allow users to access their mailboxes.

You still use the Exchange Server Deployment Tools to go through the standard deployment steps, but during Exchange Setup, you choose not to join an existing Exchange 5.5 organization.

With this method, you use the Deployment Tools to install a new Exchange 2003 organization and then choose one of the following migration methods to get your users and data from the 5.5 organization to the new organization.

This method is better suited for smaller organizations. It is a simpler solution than using ADC but does not support a long period of coexistence well. An example of a good candidate for this method is an organization that plans to migrate all of their users over a long weekend.

Using Active Directory Migration Tool (ADMT), followed by the Exchange Server Migration Wizard is a simple method of migration that does not require setting up an Active Directory connector. In this method you will use ADMT to create active user accounts in Active Directory. Once those accounts are created you will move the user's mailbox from Exchange 5.5 to Exchange 2003 and associate it with their new user object in Active Directory. This is a good option for small companies that do not have many mailboxes to migrate. See How to Migrate from Exchange 5.5 to Exchange 2003 Using the Active Directory Migration Tool > Migration Wizard External Migration Path

This method is more complicated to implement, but it is more robust. This method better suits larger organizations that anticipate an extended period of coexistence between the two organizations.

This method invovles ADC and is more complicated than the two step method mentioned earlier. It is best used in larger organizations because it allows users to send and receive e-mail messages during the migration process. In this method you will move user accounts to Active Directory, set up ADC, and finally use the Migration Wizard to move Exchange data from the Exchange 5.5 organization to the Exchange 2003 organization. See How to Migrate from Exchange 5.5 to Exchange 2003 Using the Active Directory Migration Tool (or Windows Domain Upgrade) > ADC > Migration Wizard external migration path.

The following resources contain information about using the external migration path method to deploy Exchange 2003: