Currently running Exchange 2007 SP1 on a Windows 2003 CCR clustered environment. Is it necessary to update the AD schema before upgrading to SP2?

Yes, it requires to update the schema either before upgrading SP2 or setup takes care of schema update if you have Schema and Enterprise Admin rights during first Exchange server upgrade process... From the Release Notes of SP2: -==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==- You must prepare ActiveDirectory and each domain before you perform the first installation of Exchange2007 SP2 in an organization. This process includes updating the ActiveDirectory schema for Exchange2007 SP2. For information about the required permissions and steps that you must follow to complete this process, seeHow to Prepare Active Directory and Domainsin the Exchange2007 SP2 online Help. For a list ofActiveDirectory schema changes that are made when you install Exchange2007 SP2, seeActive Directory Schema Changes (SP2).After you have prepared ActiveDirectory and each domain, you can install Exchange2007 SP2 by using an account that has been delegated the Exchange Organization Administrator role. -==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==- Microsoft Exchange Server 2007 Service Pack 2 (SP2) Release Notes http://www.microsoft.com/downloads/details.aspx?FamilyID=ee7829a3-0ae8-44de-822c-908cd1034523&displaylang=en Amit Tank | MVP Exchange Server | MCITP: EMA | MCSA: M | http://ExchangeShare.WordPress.com