Hi We have recently merged with another company and our company is going to be made a child domain in the new companies current domain. We are going to create the new child domain and use Active directory migration tool to migrate all the users from our current domain to the new child domain. Both companies are currently using Windows server 2003. The parent company use Exchnge 2003 the same as us. However We are planning on building a new exchange server for our company in our new child domain. We would like to use Exchange server 2007. Is it possibly for us to join an Exchange 2007 server to an existing Exchange 2003 organization or do we have to wait until the parent company upgrade there Exchange organization to 2007 untill we can install 2007? Regards Kevan

Yes, ex2k7 can be introduced in ex2k3 environment. There are some major differences that you shall keep in mind. 1. the all coexistence will consume a lot of time both of deployment and admin 2. Routing group connectors must be enabled for message transfer between two Exchange versions. 3. all ex2k7 servers are automatically installed in a single AG (FYDIBOHF23SPDLT) when ex2k7 is installed 4. You can use the Exchange tasks in ADUC to manage ex2k3 mailboxes. In ex2k7, you must manage servers and mailboxes by using EMS or EMC. The related management tasks to configure ex2k3 recipients have also been moved to EMS or EMC 5. There are many more differences between 03 and 07, please see the following related link for more detailed step to deliver 07 to 03 org. See more for learning how to install ex2k7 into ex2k3: Coexisting with Exchange Server 2003 and Exchange 2000 Server http://technet.microsoft.com/en-us/library/aa998604(EXCHG.80).aspx Exchange Server 2007 and 2000/2003 systems management co-existence http://msexchangeteam.com/archive/2006/10/09/429135.aspx