Hello Everyone, 

I am currently in the process of setting up coexistence for exchange 2007 and 2013. My understanding is that all the internal URL's from 2007 must be configured to be the same in 2013 and then all the DNS records will be changed to point to the 2013 server. The problem I have run into is that all the internal URL's including the SCP use the 2007 server's name. I am not sure how to proceed, can I just use a new internal URL for the 2013 server and change the SCP? Will Autodiscover then just point my existing clients to the 2013 server? I don't think I can repoint the 2007 servers primary DNS record to the 2013 server without causing multiple issues. I tried to create a legacy dns and changed the 2007 server settings described in http://blogs.technet.com/b/meamcs/archive/2013/07/25/part-1-step-by-step-exchange-2007-to-2013-migration.aspx and I ran into all kinds of mail transport issues.  We are also using a Barracuda spam firewall appliance and Cisco IronPort secure email.

Exchange 2007
IP address: 10.0.1.2
Server Computer Name: mlsrv.domain.local 
Internal URL's : mlsrv.domain.local
External URL's (only setup for owa): mlsrv.domain.com


Exchange 2013 
IP address: 10.0.1.3
Server Computer Name: EX13.domain.local
Internal URL's: ??? 
External URL's: ???

Thanks,

You don't need to set all URLs to point to 2013. This requirement only applies to AutoDiscover. I.e. AutoDiscoverServiceInternalUri and whatever DNS record you have set for autodiscover should be pointed to 2013.

Apart from the above given suggestion, I would refer you on below mentioned references that provides step-wise instructions by covering all the required aspects in order to accomplish this task without getting interruptions : http://twarog.net/guides/exchange-2013/exchange-2007-to-2013-upgrade-migration-guide/32211

Also, http://www.msexchange.org/articles-tutorials/exchange-server-2013/migration-deployment/planning-and-migrating-small-organization-exchange-2007-2013-part8.html

Moreover, while need to migrate users mailboxes from Exchange 2007 to 2013, this automated solution (http://www.exchangemailboxmigration.com/) could also be a good alternative approach to get this job done without downtime.

I would say is to look at these links:

http://blogs.technet.com/b/meamcs/archive/2013/07/25/part-1-step-by-step-exchange-2007-to-2013-migration.aspx

And the Exchange Deployment Assistant:

https://technet.microsoft.com/en-us/exdeploy2013/Checklist?state=2419-W-AAAEAAAAQACIAAEAAQAAAAA~

I would also like to say, that the native Exchange Mailbox move from Exchange 2007 to Exchange 2013 is an online move, meaning the user stays connected to Exchange until the move request completes and cuts everything over to Exchange 2013.  At that point they will receive a prompt to restart Outlook and they will need to restart Outlook to gain access to their mailbox again. While I haven't used a third party tool to perform this work, I would think that the behavior is the same if you use a third party tool.