Upgrading from Exchange 2007 to Exchange 2010

Exchange 2007 and Exchange 2010 can coexist.  But you will have to upgrade the Active Directory Schema, Forest Configuration and Domain Configuration.  This does not mean that you have to implement a 2008DC.

https://www.simple-talk.com/sysadmin/exchange/upgrade-from-exchange-2007-to-exchange-2010---part-1/

You can also read more on Exchange 2007/2010 Co-existence here:
http://technet.microsoft.com/en-us/magazine/jj542449.aspx
and here:
http://blogs.technet.com/b/jribeiro/archive/2009/11/26/transitioning-from-an-exchange-2007-environment-to-exchange-2010.aspx

-saige-

Hey Carilou,

Any reason you are not going straight to Exchange 2013?

We bought the software 2 years ago.  More of a financial decision than anything.

In looking through the articles, it seems that having the 2 Exchange servers coexisting is more work than necessary.  I would like to get any feedback on a clear upgrade path of a 2003 server with Exchange 2007 to a different 2008 R2 server with Exchange 2010 that can be completed over a weekend.  The path of least resistance is what we are looking for, as this is a small organization with 25 mailboxes, many users remoting in through a RDP server and all needing their smart phones accessing email.

Thank you Saige that is good to know.  We also are preparing to move to a new 2008 Domain Controller (currently our DC is a 2003 server).  Would you suggest we perform the domain controller move first, before we bring the new exchange server into the mix?

According to the Exchange Server Supportability Matrix;

Exchange 2007 SP3 RU13 or later, is supported in environments where the AD Controller(s) are all running Windows Server 2003 SP1 (or later) with a minimum domain functional level of Windows Server 2003 and a maximum domain functional level of Windows Server 2012; and a minimum forest functional level of Windows Server 2003 and a maximum forest functional level of Windows Server 2012.

Exchange 2010 SP2, is supported in environments where the AD Controller(s) are all running a minumum of Windows Server 2003 SP2 with no Windows Server 2012 R2 servers; with a domain and forest functional level that is constrained by the same supported levels as Exchange 2007.

Exchange 2010 SP3 RU5 or later, has the same requirements of Exchange SP2 with the exception that it is supported in environments with Windows Server 2012 R2 servers; and has no constraints with regards to the domain and forest functional levels as long as they are, at a minimum, Windows Server 2003 or higher.

In short, you do not have to add your Windows Server 2008 Active Directory server first, but there would be nothing wrong with doing so.  Just make sure that the functional levels of your Active Directory domain and forest are set properly.

-saige-