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Exchange Server migration | Large organization requiring continued access to OWA and mobile access during migration


I am in the process of migrating Exchange 2003 (on Windows 2003) to Exchange 2010 (on Windows 2008 R2).
I know that as I move users' mailboxes from 2003 to 2010, their OWA and mobile phone will no longer function.  I am looking into options to allow a smoother transition.
I have reviewed a document that allows for a co-existence which would require co-existence.  This seems to be quite involved, and I was wondering if there is an options that falls somewhere in between.  Is it at all possible to have the following:

•Current users access OWA and configure their Smart Phones connecting to https://webmail.domain.com/exchange.
•Exchange 2010 is being configured to use https://webmail.domain.com/owa for the same purposes.
Sacrificing the automatic redirection, is it possible to do this:
 •Configure a separate host so that OWA to Exchange 2010 is https://webmail2.domain.com/owa 
•Install a separate SSL for webmail2.domain.com
•Once a mailbox is moved from 2003 to 2010, simply reconfigure the phone to use the new address.
I realize that this may be a dumb question, but I am curious to see if this is even an option.
Thanks in advance for your input and assistance.
5 Solutions
AmitIT ArchitectCommented:
You simply need to cut over your OWA and AS to 2010 and set the legacy Exchange redirection from 2010 to 2003.
Check this
Simon Butler (Sembee)ConsultantCommented:
Coexistence is easy, I am currently doing 9000 mailboxes for one of the UKs largest restaurant chains, completely without any disruption.
Simply configure a legacy URL for Exchange 2003, pointing the existing URL at Exchange 2010. ActiveSync and Outlook Anywhere will proxy to the older version if configured correctly.

The method you have outlined will work and for some ActiveSync clients you may not even need to reconfigure them to use the new URL as Autodiscover will do the work for you. However it isn't a method I tend to use because it can cause some confusion, particularly for OWA. As ActiveSync proxies it seems additional work for little gain, when the legacy redirection can be setup in a few minutes.

Your worries are the same as many of my clients.  You have no other option but upgrade in "Co-existence" or "Swing Mode".

I don't recommend  the change of URL as this can bring some problems to users settings and you may have to include a new name on your SSL or get a new one when you can keep your existing one.

More info:  Exchange 2010 doesn't install autodiscovery by itself, like 2013 you will have to do it, regardless the version you change to your actual server won't stop being your main exchange server until you change your DNS MX and A records and your firewall to redirect the traffic to the new server.  Keep this in mind!!!  Also, as pointed by Simon once you have installed your new Exchange and make it your main one it should have everything to connect directly to the old one.

Remember, OWA is a "Web Site" residing on you Exchange server and what it does is grant access to a user mailbox.  Now the way this access is granted is what you should be concern to have your user's access without hassle. I will explain further later.  There is no way you can emails interrupted, even if this is only for a few minutes or hours per mailbox...why? because the whole purpose of the migration is to move the mailboxes to a new server therefore when you are going to perform this move at aprox. 45% of it the user will loose connection to its mailbox by any access service.  Once the move is completed the user will regain access to it and he/she will be inform to close the client and re-open it.

I'm guessing you have right now access to your mailboxes via services (OWA, ActiveSync) username-password combination but on 2010 this is changed to domain\username-password.  You will have to open your EMC on 2010 and expand Server Configuration to find Client Access and on the middle section of the screen find the tab "Outlook Web App" and open the properties to find authentication and select the method you need.

You will also may have to change your access authentication for ActiveSync. (Same section as above, just open the tab for ActiveSync).

If you have any user accessing by POP or IMAP you may change the authentication of those too to match your actual settings and make sure the service is set to start automatically. (Most of the time Plain Text, this is the default method for most BlackBerry phones).

Ah!! one more thing...very important!!!! set or remove your database limits for mailboxes before you start moving the old ones cause this can cause a mailbox move failure and frustrate some users cause they will be interrupted twice! and restart your IIS after all the changes.

Here is a good Step-by-Step you can follow:  http://www.petenetlive.com/KB/Article/0000234.htm

Good Luck
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Simon Butler (Sembee)ConsultantCommented:
"More info:  Exchange 2010 doesn't install autodiscovery by itself, like 2013 you will have to do it,"

I need to pull you up on that.
There is no "install" of Autodiscover involved, so I am not sure what you are referring to here.
The only thing that Exchange installation doesn't do is set URLs for internal Autodiscover. That can lead to conflicts within the domain if you aren't careful, because you have two servers publishing Autodiscover information to the domain.
Autodiscover is there right out of the box, and will work (just with SSL errors).

Simon:   I don't know if there is something wrong with the way I do my "Swing Mode" migration from 2003 to 2010 but autodiscovery was never installed.
Simon Butler (Sembee)ConsultantCommented:
There is nothing to install for Autodiscover - it is part of the base product of Exchange 2007 and higher. That is why I had to say something.

realtimerAuthor Commented:
Thank you everyone.  I'll work with these recommendations.
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