Migrating from Exchange 2003 to 2010

msidnam used Ask the Experts™
I'm in the process of upgrading from Exchange 3003 to 2010. I've been searching online and have been reading a book I purchased (Microsoft Exchange 2010 Unleashed). They sure have changed it a lot. Particularly the area where you no longer connect to the server with the maillboxes but instead to a CAS server. Our environment is fairly simple:

Roughly 300 users

2003 AD. One Forest one domain (This weekend is our upgrade for our first 2008 DC. we've already done forestprep and domainprep)

Exchange 2003 Front End server in our colo where all of our email currently goes in and out of via and internet mail connector. this FE is the local bridgehead and send emails via smarthost to our cloud service (Mcafee/MXLogic)

Exchange 2003 backend server located in our main office where all of the mailboxes reside. This server, if the one in our colo goes down, will accept and send email if needed. I just change the MX records in my Mcafee console login.

Currently users using EAS connect to the server with the mailboxes directly.

Mix of windows XP (outlook 2003) and Win 7 (outlook 2010)

One Blackberry Server

We have hundreds of DL's.

Thats pretty much it in a nutshell. During my research it looks like i need to install a CAS server in our colo first, replacing the 2003 FE. Then I install a CAS and mailbox server on the same machine in our main location. Reason for having CAS role is in case the one in our colo goes down and i need to reroute emails to that mains server.

My questions are:
1. is this the proper order?
2. MS did away with Internet mail connectors and such (if im thinking correctly) so i have no idea how the 2003 and 2010 servers will coexist (i know its possible but havent found any great detail) and how i send via smarthost to MCafee
3. Should i put the CAS and mailbox server on the same host? Will it degrade performance?
4. Do i have the order of installed servers correct?
5. Anything i should be aware of?

Thank you for the help.
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1. CAS first, then Hub, then MBX is the proper order if installing individually.

2. When you install your first 2010 HUB, a new Exchange 07/2010 "Legacy" routing group will be created, and a RGC will be created between this RG and your current Exchange 03 RG. If you have more than a single 03 RG, installation will prompt you to select the 03 RG with which to establish the RGC between 03 and 2010. All external (inbound/outbound) mail flow will still go through the 03 servers.

By default, the only mail going to/from 2010 will be via that RGC created by setup, and only if there are mailboxes on a 2010 MB server. Also, out of the box, there are no 2010 send connectors and the default receive connectors will not facilitate internet email inbound or outbound, so everything will still flow through 2003.

3. For 300 users, you shouldn't notice any performance issues unless you are running very low RAM, slow disks, or very weak CPU's.

4. Refer to #1

5. It's not a terribly difficult process in this small environment, but you definitely want to read up on the process. If you can, test it out in a lab environment to get comfortable with the process.

Here are some additional readings for you:

And finally the Ex2010 deployment assistant:


Would i need a HUB server if i only have one domain and no connections to other domains?

Absolutely required, it's the only thing that can send/receive mail directly to and from the mailbox role. Exchange will not allow you to install the mailbox role without installing the hub role first (or simultaneously). Keep in mind you can install all exchange 07/2010 roles on a single box (except edge which has to be solo) or mix/match to your specs.
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Since I have an FE at my colo, im thinking i should replace that with a CAS and HUB? CAS to accept client logins and hub to talk to the server in HQ. And then at HQ set it up as a CAS, HUB and MBX Server? CAS and HUB just in the case the one in the colo goes down and i need to reroute.

While often debated, it is an unsupported configuration to have a CAS in a DMZ scenario, much like your colo scenario. (I assume your term colo is referring to colocating a server with a third party provider and NOT part of your actual infrastructure.)

I would suggest to you the following: why not have a second 2010 server on premises configured as a DAG and redundant CAS/HUB? You already utilize a hosted filtering service that will queue mail for you if a failure occurs.

If your term colo is referring to a second site in your infrastructure, then you could place a second 2010 server with CAS/HUB/MB roles in a DAG for a site resilient config.

If you are determined to utilize a colo (assuming my interpretation of your colo is accurate), then you would be much better served with a reverse proxy and 2010 edge role or something like ISA or ForeFront TMG/IAG for reverse proxy functionality.


Correct, we use the colo as part of our infrastructure (like a branch office). We are connected via 100mbps lines. We were using it as a DR but in the next couple months we will be moving all of our server from HQ to our colo. Our DR site will then be somewhere in MA.

One main reason i have the current FE in our colo is because the internet lines their are much faster and have better uptime. I wanted to mimic what we have now and keep the mail flow to our colo if possible.  

If I were in your shoes, I would be inclined to coincide the transition to exchange 2010 with the moving of all servers to the colo site, and have both 2010 servers located there configured in a DAG. If you are moving all servers there anyway, I would keep it simple.

If that's not feasible then I would proceed with a 2010 server in each location configured in a DAG. When you then decide to move everything, you can simply repoint the DAG FSW to a server in the colo, and activate the db copy in the colo to facilitate an easy switchover when you move.


Is it true that I need windows 2008R2 ENTERPRISE to install DAG? Or can it be done with standard?

Windows 2008/2008R2 enterprise is required, but Exchange 2010 can be just standard edition. This is because DAGs require the clustering components of the OS.


Thank you. time to format and put in Enterprise :)


All of your comments have helped.

Glad to help let me know how it goes!


sorry about this as i know the question is closed, but would you be able to clarify a few things for me? im in the process now of installing and im going to try and mimic what i have now until we get to our new colo. I would wait, but our current exchange server is having a terrible time keeping up with the current usage (constant "trying to connect to server.domain.com").

I think we are going to end up going with your suggestion with the DAG's but I need to mimic, if possible, what we have now until we move to our new colo (could be a few weeks). If i remove the current FE and install the CAS (would i need HUB on that too?) in the colo will email still flow to both 2003 and 2010 servers (as long as i configure it correctly of course)? Then in my HQ create the server as a CAS/HUB/MBX? I would put all 3 roles in case the colo goes down for some reason and i need to reroute emails. Will the outlook clients know which server to connect to? If i have to CAS roles does it go to the closest one or will it try the one in the colo?

If you think i need to make another question let me know. I dont want to take advantage.

Thank you.

It's up to you regarding the new question thing... you may want to since this one will get little attention since it's closed.

If I were in your shoes, I would have all 3 roles installed in each location, configured in a DAG. During installation of the HUB, setup will create a "Legacy" routing group that all Exchange 2007/2010 servers will be placed in. A RGC will also be created between the 2010 "legacy" routing group and an 03 routing group; if you have more than 1 2003 RG, setup will ask which one to establish the connector with.

Then regarding the CAS and FE stuff; establishing coexistence here will involve some planning. You could do a quick cut-over where you put 2010 CAS in and remove 2003, but will potentially involve downtime. You can also plan for coexistence during your transition, which will be more tedious, but will eliminate the "shotgun approach". I've performed several projects from both angles, and it just depends on the scenario as to which is the best option.
Here's some reading on the subject:



Would it be possible to keep to the current FE up and running to keep mail flow out of our current colo until we move? i was thinking of creating the CAS/HUB/MBX in HQ but keeping the FE in the colo until we move. once we move i'll remove it and the old 2003. ill be sure to get the mailboxes off of the 2003 before that.

if i cant, then what i can do is just remove the 2003 FE altogether and route all mail to HQ until we move to the colo.

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