Deploying Exchange Legacy Servers into an Exchange 2010 organization - TechNet Articles - United States (English) - TechNet Wiki

This Exchange TechNet Wiki page explains in which scenarios it’s supported and not supported to deploy an Exchange 2003 or 2007 server into an Exchange 2010 organization.

Exchange Server 2003

If you have a pure Exchange 2010 RTM or Exchange 2010 SP1 based organization (that is an Exchange organization consisting specifically of Exchange 2010 servers) , you cannot deploy new Exchange 2003 servers into the organization.

If the Exchange organization had Exchange 2003 servers deployed prior to the deployment of Exchange 2010 and at least one Exchange 2003 server still exists in the organization, you will be able to install new Exchange 2003 servers into the organization at a later time.

Note
Even if you decommissioned the last Exchange 2003 server, you can still install the Exchange 2003 System Manager tools on a server in the Active Directory domain.

Exchange Server 2007

If you have a pure Exchange 2010 RTM or Exchange 2010 SP1 organization (that is an organization consisting only of Exchange 2010 servers) and never had at least one Exchange 2007 server deployed, you cannot deploy a new Exchange 2007 server into the organization.

Bear in mind that it’s not from the moment where you deploy the first Exchange 2010 server, you are blocked from introducing an Exchange 2007 server. This is the case as soon as the Active Directory has been prepared for Exchange 2010 using the Setup /PrepareAD command.

Note
It's supported to install Exchange 2007 servers into an Exchange organization where the schema was extended using Exchange 2010 SP1 bits.

If no Exchange 2007 servers are detected, you will get the warning shown below, when preparing the Active Directory using the “Setup /PrepareAD” command.

If the Exchange organization had Exchange 2007 servers deployed prior to the deployment of Exchange 2010 and at least one Exchange 2007 server still exists in the organization, you will be able to install new Exchange 2007 servers into the organization at a later time.

Note
If the Exchange servers in the organization are running Exchange 2010 SP1 and you need to install an Exchange 2007 server into the organization, make sure you use an Exchange 2007 SP3 media.

See Also