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Upgrading from Exchange 2003 to 2010

Vladimir Meloski [MCSE, MCITP, MCT, MVP]

Vladimir Meloski [MCSE, MCITP, MCT, MVP] Photo

Vladimir Meloski is a Microsoft Certified Trainer and Most Valuable Professional on Exchange Server. He is a consultant, providing unified communications and infrastructure solutions based on Exchange Server and System Center. Vladimir has been involved in Microsoft Conferences in Europe and US as a Speaker, Proctor for Hands on Labs and Expert.

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In this article we will describe the process of upgrading an Exchange organization from version 2003 to 2010. We start from the introduction of the first Exchange 2010 server and complete it with the decommissioning of the last Exchange 2003 server.

Microsoft Exchange Server 2010 brings a new set of great technologies. No surprise many are excited and looking forward to plan and deploy this new messaging infrastructure. Today we cover the basic steps that should be performed in organizations currently running Exchange 2003.


Prerequisites that must be met before we start the deployment:

  • Windows Server 2003 SP2 or later, Global Catalog servers in each site where Exchange Servers are located and Windows Server 2003 forest functional level.

  • Exchange 2003 Organization must be in native mode, with Exchange 2003 SP2 installed

  • In place upgrade is not supported, thus new hardware should be installed for the Exchange 2010 Servers. Hardware requirements may be found at the following link:

  • Operating Systems supported are Windows Server 2008 SP2 64-bit and Windows Server 2008 R2 64-bit Standard or Enterprise. Please note that Exchange Server 2010 is 64-bit only, i.e. there is no 32-bit version available for testing purposes and there are no 32-bit management tools. Management tools should be installed on a 64-bit operating system too.

  • If the organization has multiple sites, the first site to introduce Exchange 2010 should be the internet facing site. The upgrade then continues with non-internet facing sites.

  • If the solution design requires installing Exchange 2010 roles on multiple servers, then these should be installed in the following order:

    1. Client Access Server role
    2. Hub Transport Server role
    3. Unified Messaging Server role (optional, may be deployed later)
    4. Mailbox Server role
    5. Edge Server role (optional, may be deployed later)

The Installation Process

The installation process requires Active Directory to be prepared. In order to do that, the user should be member of the Schema Admins and Enterprise Admins security groups.

When transitioning from Exchange 2003 to 2010, we transition the Exchange specific permissions using the command that follows.
setup /PrepareLegacyExchangePermissions or setup /pl

The Active Directory schema must be extended with Exchange 2010 specific attributes thus we run:
setup /PrepareSchema or setup /ps

The next command to run is:
setup /PrepareAD or setup /p

This performs multiple tasks. It verifies that the schema has been updated, assigns specific permissions in the configuration partition, creates the Microsoft Exchange Security Groups organizational unit (OU) in the root domain of the forest, and prepares the local domain for Exchange 2010.

The last command of the preparation steps is:
setup /PrepareDomain or setup /pd

This also performs multiple tasks. It creates a new domain global group named Exchange Install Domain Servers in the current domain. Next it adds this group to the Microsoft Exchange System Objects container and to the Exchange Servers group at the root domain.

Note: For detailed Active Directory preparation steps please check:
Prepare Active Directory and Domains

The Exchange 2010 installation steps were discussed in Installing Exchange 2010 Beta. Thus we proceed with the so called coexistence scenario i.e. the moment when there are both Exchange 2003 and 2010 versions present in our organization.

In order to provide message transport coexistence between both versions, the setup will perform the following actions:

  • Ask for the Exchange 2003 bridgehead server to be identified

  • Create an Exchange Routing Group RG (DWBGZMFD01QNBJR) to host Exchange 2010.

  • Create routing group connectors between the Exchange 2003 bridgehead RG and the Exchange 2010 RG.

  • Create an Exchange Administrative Group AG (FYDIBOHF23SPDLT) to host Exchange 2010.

Since Exchange 2007, administrative groups and routing groups are no longer used. The same also applies to Exchange 2010. Thus the RG and AG are only created to allow coexistence with Exchange 2003. Furthermore the groups are only visible from the Exchange 2003 System Manager console. It is not allowed to make any configuration or membership changes to both of these. Again, same as in Exchange 2007, Exchange 2010 uses Active Directory sites instead of Routing Groups to define the routing topology.

Exchange 2003 System Manager

Client Access Server Role Coexistence

So far we completed the Exchange 2010 setup. We now configure the server roles.

During the coexistence phase, we should change some DNS settings to provide a seamless transition. Let's assume our current Exchange 2003 server is accessed by name After installing Exchange 2010, a legacy name should be assigned to identify the Exchange 2003 infrastructure, for example we use This is done both at the internal and external DNS namespaces. In addition, the current DNS host name ( is assigned to the new Exchange 2010 server. Thus clients won't use the legacy name, they still continue to access their mailboxes without changing settings.

A new certificate should be issued because of Exchange 2003 and Exchange 2010 coexistence. Wildcard certificates and certificates that support Subject Alternative Names may be used.

We will assume that the primary external namespace for virtual directories is configured during the setup (for example Clients will use this name to connect from the Internet.

Coexistence between Exchange 2003 and Exchange 2010 Client Access will be provided by configuring the URL property on the /owa virtual directory. This is done from the Exchange Management Shell using:
Set-OWAVirtualDirectory "MAIL2010\OWA (Default Web Site)" -Exchange2003URL

If our company uses Outlook Anywhere, it should be enabled from the Exchange Management Shell using:
Enable-OutlookAnywhere -Server:MAIL2010 -SSLOffloading $false

In addition, forms-based authentication on the Exchange 2003 front-end server should be configured in order to have single sign-on between both versions.

The Offline Address Book generation service should also be moved to the Exchange 2010 CAS Role. From the Exchange Management Shell use the command that follows:
Move-OfflineAddressBook "Default Offline Address List" -Server MAIL2010

To enable Exchange 2010 and 2003 to communicate using Kerberos authentication, the configuration partition in Active Directory should be changed, so that the attribute msExchAuthenticationFlags of the Microsoft-Server-ActiveSync object is set to value 6.

At this point in time, all clients are connecting to the new Exchange 2010 Client Access Server using the name The mailboxes are still on Exchange 2003, so the Outlook Web Access experience is actually version 2003. They will connect to the new version of Outlook Web Access once their mailboxes are moved to Exchange 2010.

User Comments - Page 1 of 1

KM 11 Jun 2012 02:21
Please share me the notes on how to do the upgrade, as I am still running Xchange 2003 on the network but now want to migrate to 2010 with production srvr but want to try to limit the downtime time!!

I have prepared my box (2008 srvr 64bit) to host the 2010 while the other box still running server 2003 and xchange 2003!

Need to upgrade SBS 2003 to SBS server 2011 on new hardware along with exchange server 2003 to 2011 20 Oct 2011 06:34

I need to update the exchange server 2003 to exchange server 2011 and need all my data,mailboxes on new exchange server in new server hardware?

How can I do that?
Does it doable remotely?

Also We have SBS 2003 DC and need to install SBS 2011 or SBS 2008 enterprise, how can I install all 2003 DC settings(ADS) on SBS 2011 or WIn Server 2008 enterprise?

please send your valuable answers at


Roshi Singh
Need to upgrade SBS 2003 to SBS server 2011 on new hardware along with exchange server 2003 to 2011 20 Oct 2011 06:31

I need to update the exchange server 2003 to exchange server 2011 and need all my data,mailboxes on new exchange server in new server hardware?

How can I do that?
Does it doable remotely?

Also We have SBS 2003 DC and need to install SBS 2011 or SBS 2008 enterprise, how can I install all 2003 DC settings(ADS) on SBS 2011 or WIn Server 2008 enterprise?
Satish 12 Jul 2011 22:52
Dear All,

I followed few articles on net and was able to install Ex2010 in co-existence with 2003. Now a very strange things is happening. If i move any mailbox from Exchange 2003 to 2010 it doesnt receive any mail. Even a mail to itself doesnt get delivered. If i create a new mailbox in Exchange 2010 then it can receive and send mail without any issue. I am not able to get why its happening. Any help will be appreciated..

Thanks n advance.. 21 May 2011 08:14
This was very well written and concise.
Charles 15 Apr 2011 07:33
Hello Frank Bicocchi, i am in the middle of an Exchange 2003 to Exchange 2010 transition. I plan to do a onetime cutover/move request of all mailboxes, on a weekend. So far everything's good.I would like to ping with you and ask a few questions especially the steps to the coexistence mode in case i decide to implement it within the time frame i have for this project.Thank you very much for your response.If you decide to email me, my address is Thanks again.
PeteLong 4 Apr 2011 09:00
Heres some info you might find usefull
TST32TL 30 Mar 2011 14:08
Does anyone know if I can completely skip Public folder database during the upgrade from Exchange 2003 to 2010? That means in the new environment, I don't need it, I don't want it. Can it be deleted or removed completely without doing transfer of replicas?
Thomas Deliduka 17 Mar 2011 14:25
I don't know if you can answer this (if you're monitoring comments). This is a question about semantics. We have a server we'll call it "exchange1" that we're building as our new exchange server and we were going to have the CAS role be on "exchange2". According to your article. it sounds like I need to be building "exchange2" first before I install "exchange1" so the server roles are on the right servers. Is that right?
Alexander Zammit 10 Feb 2011 15:00
Thanks for sharing your experience Frank
Frank Bicocchi 10 Feb 2011 13:30
I had just performed an exchange 2003 to exchange 2010 migration. First off, this went flawless! I was so happy with the outcome. As many of you know, Exchange 2010 requires 64 bit OS. THEREFORE, I started the projected by creating a new 64-bit Windows 2008 enterprise server and a new windows 2008 64 bit enterprise domain controller in an existing 2003 active directory environment. First, let me say that you have to run adprep off the 2008 cd on your DC that holds your fsmo roles. I installed exchange 2010 and brought up a new BES 5.0.2 server as I thought this would be an excellent time to refresh corporate blackberry users. I love this version of exchange! I was running co-existence mode until the migration was complete and then I uninstalled exchange 2003 from my environment and retired that old clunky exchange server. Let me say that despite the noise about making your client access and mailbox role a VM. I had no issue doing this, as I am a huge VMware and virtualization fan. I have had no issue with my cas, hub, and mailbox roles all in one VM with zero performance issues. One thing I do not like is that by design store.exe is now a memory hog! However, there are parameters that you can use in adsiedit.msc where you can limit the memory usage of store.exe that work great! All in all the only complaint I got was from the helpdesk, as they cannot install Exchange management tools on their desktops because they run 32 bit OS. I told them to upgrade their desktop OS to 64 bit so they can run the tools. I know they make some third party management tools that allow your helpdesk to still perform common exchange tasks but I am NOT a big third party fan. If anyone has any questions about more details about my migration from exchange 2003 to 2010 I will be more than happy to answer them. In addition, when you plan your exchange 2010 rollout one big thing to remember here is give yourself plenty of space for the info store lun as exchange 2010 does NOT like to have less than 2 gb free space of the store lun or luns. If it goes below 2 GB mail will stop flowing and will not flow again until you free up some space.
Frank Bicocchi
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