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Installing Exchange Server 2010 in Mixed Mode Environment – Part 1

Posted by Milind Naphade on 27/10/2009

Per the latest news from MS Exchange Team Exchange 2010 is out to manufacturing. With that said, it will be available for the production deployments very soon. In this series of posts I am covering the installation of Exchange 2010 in a mixed mode environment.

Though it can be installed with the legacy version of Exchange there are certain pre-requisites you must fulfil. In this post we are trying to uncover the installation method of Exchange 2010 in an existing Exchange 2003 Organization. So, even before you start installing Exchange 2010 you have to do some preparation on your Exchange 2003 side. Very important and must be understood fact about Exchange 2010 is it can not be installed with any other version of Exchange prior to Exchange Server 2003 SP2. So, if you have an Exchange 2000 Server and planning to transit to Exchange 2010 you must upgrade it to Exchange 2003 SP2 first. Following table illustrates the supportability of co-existence:

Version of Exchange Exchange Organization Co-Existence
Exchange 2000 Not Supported
Exchange 2003 Supported
Exchange 2007 Supported
Exchange 2003 and 2007 together Supported


Once you have understood the supportability of the Exchange 2010 setup and you think that you are good to go, you will have to work a little bit on your Exchange 2003 organization first of all. So, this work out will contain raising the AD DFL, AD FFL and Exchange 2003 org functional level.

1. The first step would be raise your AD Forest Functional Level and AD Domain Functional Level to Windows Server 2003 at least. After changing the DFL or FFL you may need to wait till the replication in your entire AD forest completes.

2. You must change your Exchange 2003 org to operate only in Native Mode. That means it simply discards the support to any Exchange 5.5 servers in your Exchange 2003 org. If you are still running Exchange 5.5 site with your Exchange 2003 it must be migrated over to Exchange 2003 and then decommissioned before changing your Exchange 2003 org mode. To change your Exchange 2003 org to native mode, right click on your Org Name in ESM and select Properties. The Org Properties dialog box appears. Click on the Change Mode button. You will be warned that this setting is irreversible.


3. Considering your AD health, replication and DNS are working absolutely fine you can now think of starting for Exchange 2010 preparation. So what we need here to install Exchange 2010 is either Windows Server 2008 SP2 or Windows Server 2008 R2 which is available only in 64 bit flavour and of course powerful enough hardware to install a 64 bit architecture OS on it. The minimum and recommended system requirements can be found at:,EXCHG.149).aspx

4. Assuming that you have already setup a Windows Server box installed Windows Server 2008 SP2 or Windows Server 2008 R2 on it, its time to configure it to install Exchange 2010 on it. Here, you might notice that Exchange 2010 will still support Windows Server 2008 but it must be installed with SP2. Exchange 2010 can support both of these operating system versions. Yet, the OS configuration part varies due to changes in architecture of both versions. Though the software component prerequisites remain the same on both versions they have their own ways to configure these components. Microsoft already has a publication on technet which talks about the ways to install these software prerequisites. They can be found at Exchange 2010 Prerequisites. It is highly recommended that you should run Windows Update before starting an install of Exchange 2010. Windows update will download all the latest updates for the software components.

Natively, Exchange 2010 will require following software installed on a Windows box:

1. .Net Framework 3.5 SP1 – Exchange code base is built on .Net Framework 3.5 where the Exchange 2007 had it built around 2.0 (Not required to be installed on Windows 2008 R2)

2. Windows Remote Management Tools 2.0 and Power shell V2 (Not required to be installed on Windows 2008 R2)

3. 2007 Office System Converter: Microsoft Filter Pack. (Required to be installed on the servers hosting mailbox server role or hub transport server role)

Apart from these additional software below is the list of required software components need to be installed:

5. As you already have an Exchange 2003 organization setup and running, its now time to setup your first Exchange 2010 server in co-existence. If you have already worked a Exchange 2007 setup you might have been knowing to run the legacy exchange permissions preparation. Yes, in Exchange 2010 you still need to run that switch with to prepare the legacy exchange permissions. There is a known issue detected when Exchange 2007 was a RTM release that the direct install of Exchange 2007 will break the RUS permissions on Exchange 2003. Which results into RUS not stamping email addresses on new Exchange objects. The detailed information is give at Preparing Legacy Exchange Permissions


6. Wait for replication to complete and then you can go ahead with another step of preparing the forest schema. Indeed that’s again similar to Exchange 2007 /PrepareSchema.


You can see the new schema objects being inserted into the Schema partition while the setup goes on or after its completion.

image 7. Once you are done with all above steps now its time to install Exchange Binaries which actually form a Windows Server 2008 box to an Exchange server. At this stage you can either chose to go with the GUI based installation or simply with the command prompt. GUI based installation is always simpler method to go with as it avoids confusions many times. I prefer using command like but for those who are not very comfortable with powershell or command line tools its a good practice to use GUI as far as possible.

Now, before you start installing make sure that you have met all the software component prerequisites on the exchange 2010 box. Again, you may refer the link Exchange 2010 Prerequisites

In the next part of this post I will explain on how to install and what to configure on Exchange 2010 side as there isn’t much that you have to modify in an existing Exchange 2003 server. So stay tuned and do post your comments and your opinion about this post.


 Related Posts:

Installing Exchange Server 2010 in Mixed Mode Environment – Part 2


2 Responses to “Installing Exchange Server 2010 in Mixed Mode Environment – Part 1”

  1. […] Installing Exchange Server 2010 in Mixed Mode Environment – Part 1 […]

  2. Exchange Admin said

    Thank you so much, this is the only article I’ve found that explains that you need to switch your exchange mode as well. I spent an hour wondering where else I could change my domain and forest again since the error in the install program does not specify which of three are in mixed mode.

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