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Impact on Active Sync during Exchagne 2003 to Exchange 2010 Migration.

am230089 asked
This question is main on the Active sync druing the coexistance and migration phase from Exchange 2003 to Exchagne 2010.
As we are using mail.domain.com as a owa and active sync url for users in Exchange 2003 enviromnet.
Now we are migrating to Exchagen 2010SP2.
Now i have new cert with few other names.

the question is after Exchanege deployment when i configure my CAS server to SErver the Request for mail.domain.com and legacy.domin.com for request, for OWA it is ok. but When Active sync users access the mail from device , first it will go to CAS Server , CAS check the mailbox and proxy the request to legacy.domin.com(Exchage 2003) Server,
So when it will proxying the request to different address what will be the impact on the active sync ? Active sync automatic detect the chanegs ?
or give me the error messages ?
What will teh impact ?
In my oranization i have 10000 Active sync users and i can't chagne the url in the device, please advice.

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Alan HardistyCo-Owner
Top Expert 2011

Please have a read of the following MS Exchange Team blog and if you have any questions afterwards, feel free to ask:



I have already read this artical, but i don't understand completey.
That's why i have open the question.
My both the Url's are register on the Internet. but all the request will hit to mail.domain.com. just i have configure my legacy.domain.com in CAS Server for Exchange 2003 USers and active sync.
Know i am looking for some expert connents what will be the impact on the active sync users. when they hit mail.domin.com and proxying to legacy.domin.com.
Alan HardistyCo-Owner
Top Expert 2011

You are using mail.domain.com for your existing devices - is that correct?


Yes, this is the address which are users are point for Active sync and OWAS Access.
Alan HardistyCo-Owner
Top Expert 2011

Well then as long as mail.domain.com points to your 2010 CAS and you have the name mail.domain.com in the Exchange 2010 SAN / UCC SSL certificate, there won't be any issues.

Exchange won't use legacy.domain.com to access the Exchange 2003 server - that traffic is HTTP based and an internal request, so the SSL cert / cert name isn't relevant beyond the CAS server.


Ok, What will happen when active sync users access the mails and mailbox is in Exchange 2003 .

Request will start from mail.domain.com goes to CAS server , CAS serve check the mailbox server and proxy the request to Exchange 2003 server.
For Exchange 2003 we are using "Legacy " that means url will change , so is there any imapct on the active sync users.Because when you use owa with same settings url change on the internet exploere from mail.domin.com to legacy.domin.com.
So during access the mail from phone that could be the chalange .
I don't know url will chnge on the active sync users what will be the impact ?
Alan HardistyCo-Owner
Top Expert 2011

When does the Exchange 2003 server switch to being Legacy.domain.com?  If it is currently mail.domain.com then it will remain mail.domain.com.

Legacy.domain.com is only relevant for Exchange 2010 / 2007 co-existence.

Extract from link provided earlier:

"Are there any configuration changes I must make on my Exchange 2007 Client Access servers?

In order to introduce Exchange 2010 into your "Internet Facing AD Site" and support your Exchange 2007 (and possibly 2003) mailboxes, you will move the primary EAS namespace that is associated with the Exchange 2007 CAS array and associate it with the Exchange 2010 CAS array. In addition, you will create a new namespace for legacy access, legacy.contoso.com (note that the name can be anything you want) and associate it with your Exchange 2007 CAS array.


If it is not change the name that i wil serve my perpose.
Thanks for your clearification.
Top Expert 2011
Having read another article, there is conflicting information:



Installing Exchange 2010 within your organization on new hardware.


Configuring Exchange 2010 Client Access.


Creating a set of legacy host names and associating those host names with your Exchange 2003 infrastructure.


Obtaining a digital certificate with the names you'll be using during the coexistence period and installing it on your Exchange 2010 Client Access server.


Associating the host name you currently use for your Exchange 2003 infrastructure with your newly installed Exchange 2010 infrastructure.


Moving mailboxes from Exchange 2003 to Exchange 2010.


Decommissioning your Exchange 2003 infrastructure.The relevant part to answer your question is:

"After a legacy host name has been configured and associated with your Exchange 2003 infrastructure, and your current host name has been associated with your Exchange 2010 infrastructure, users will experience a seamless transition. Exchange 2010 will redirect users from the Exchange 2010 Client Access server to the Exchange 2003 front-end server. Users won't have to learn a new URL to access Outlook Web Access (called Outlook Web App in Exchange 2010) or reconfigure their Exchange ActiveSync devices. POP3, IMAP4, and Outlook Anywhere users can also continue to access their mailboxes without interruption."

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