Question

connect users on child domain to exchange on root domain

Exchange 2003, Active Directory, Windows Server 2003, Root Domain, Child Domain

My organization have AD domain on one machine including windows server 2003 and exchange 2003. The company has bought another company with difference entity, so I created a child domain with the exiting windows 2000 server machine from the new company.

Is it possible to have users on a child domain to connect to exchange server on a root domain?

Thank you in advance.

Yes it is possible, with the right ACL in place, as the trust is transitive.

---- Added by Bharat Suneja -----
Yes, it is possible and quite common to have users in child domains have mailboxes in a parent domain or a different domain in the Active Directory Forest. The Organization container resides in the Configuration partition (aka "naming context") in AD. As a result, an Exchange Organization spans the entire AD Forest. Recipients can reside in any domain in the Forest.

What needs to be done:
- Run Setup /DomainPrep in the domain where users or any Exchange servers reside (you've already done this for the parent domain where Exchange server resides. You will need to run /DomainPrep in the child domain).
- Create a Recipient Update Service (RUS) and point it to a Domain Controller in the child domain.

References:
- ForestPrep and DomainPrep
- KB 275294: Creating Exchange Recipient Update Service instances for remote domains

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