HI , I have one forest and 2 child domain with Exchange 2003 in Forest. All the users connected Outlook and OWA no issue. Last week i have migrated AD 2003sp1 to 2008r2-sp1 and installed Exchange2007 and updated to SP3. In forest no issue all users able to use Outlook and OWA. But from child domain users not able to connect outlook its prompting for the user name and password. if we provide also its asking again and again. Kindly tell me what is the mistake i have down. for the child domain users not issue there are able use OWA no issue.

Did you prep the child domain for Exchange 2007? You need to use the SP3 media. There was no need to install Exchange 2007 older than SP3, the service packs are the complete installation so you could install straight from that. What versions of Outlook is it? It could be autodiscover authentication issues. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Kindly tell me what are the steps i have to do in Child domain MS- Outlook 2007 & Outlook 2010

Running prep for child domains is documented on Technet. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Hello, You can know more information from this document: Preparing your AD for Exchange 2007 SP1 (/PrepareDomain and /PrepareAllDomains) http://blogs.technet.com/b/gerod_serafin/archive/2008/01/11/preparing-your-ad-for-exchange-2007-sp1.aspx Thanks, Evan