I have a single multirole (except for UM) 2007 server. My question is that of when I install the first 2010 multirole server and if I do not specify any external URLs during installation, will the new 2010 server take over CAS operation for my 2007 users in any form or fashion as long as I don't move any mailboxes? I am wanting to proceed very slowly and make sure everything is installed and my hardware load balancers are up and running before I have 2010 start processing any CAS requests.

will the new 2010 server take over CAS operation for my 2007 users in any form or fashion as long as I don't move any mailboxes? No, it won't ---- Even if you specify the external urls. The change happens only when you switch the DNS entry of the external URLs to 2010 CAS servers.

your 2007 users wont use that that 2010n hub for transport as well. You need to make sure that you have exch 2010 HUB server(s) avaliable so that the new exch can use for mail submission. Exch 2010 XSO model has changed therefore 2010 mailbox servers cant use 2007 HUB. You must you 2010 HUBs and vice-versa.Sukh

Agree with both of them.Gulab | MCITP: Exchange 2010-2007 | Skype: Gulab.Mallah | Blog: www.ExchangeRanger.blogspot.com

hi, agree with others and here is an article about migration steps; http://technet.microsoft.com/en-us/library/dd638158%28EXCHG.140%29.aspx http://www.networkworld.com/community/node/47778 regards, Mumin CICEK | www.cozumpark.com | Please click Vote As Helpful if it is helpful for you and Propose as Answer!!!

And in addition, here are another one that you can take a look at http://technet.microsoft.com/en-us/library/dd351133.aspxJonas Andersson | Microsoft Community Contributor Award 2011 | MCITP: EMA 2007/2010 | Blog: http://www.testlabs.se/blog | Follow me on twitter: jonand82

Thanks guys, that helped out greatly. I have a certificate question due to the multiple servers, but I will submit a new thread. Thanks again.