Dear Support, Lets says, our company have main office and branch office. I want to setup two seperate domains in two seperate forests for main office and branch office because brach office will soon become under seperate management. but based on some reasons, we need to use single exchange server which will host at main office. I don't want to build trust between these two domains. Is it possible to setup like that and if yes how can I set up? If not, please kindly point me out what is the best the way. Thanks Thu Ya Thura

You can not keep common exchange ORG for two different AD forest.The only way to establish strict boundaries between business units is to create a separate Active Directory forest for each business unit. I recommend that you use an Exchange resource forest topology, But yes you have to have trust between both AD ORG. Planning for a Complex Exchange Organization: http://technet.microsoft.com/en-us/library/aa996010(EXCHG.80).aspx Anil

Agree..Gulab | MCTS-MCITP Messaging: 2010 | MCTS-MCITP Messaging: 2007 | MCC 2011 | Skype: Gulab.Mallah

Hi, As we known , Exchange server must be in the same domain as DC except Edge Transport Server. Because Exchange server need to access the Active Directory. We can create only one Exchange organization in one forest. If you want to create two Exchange Organize on one server, it means The Exchange should have two FQDN, It should belong to two domains. It is impossible. Exchange resource forest is a good way. You only need to build one way trust membership, Exchange resource trust account forest. For how to deploy Exchange 2010 in an Exchange Resource Forest Topology http://technet.microsoft.com/en-us/library/aa998031.aspxPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.