I have two domains. One is 2008 and the other is 2000 mixed mode. They have a two way trust. I can browse each others active directory for NTFS permissions.I added a 2010 exchange server to the 2008 domain and it is working well. I am trying to add a linked mailbox for a user in the 2000 domain, but when I browse for the master account, the trusted domain does not show. I read a previous post similar to this stating upgrading the domain to 2003 worked.Does Exchange 2010 require the domains for a linked account to be 2003 or later?Thanks,Ron.

Does Exchange 2010 require the domains for a linked account to be 2003 or later? In general I would have answered yes. We have a lot of linked mailboxes. That's with Exchange 2007. In all documentation I've read Exchange 2007 with the mailboxes are in a resource forest, and the users are in account forests. This requires a forest trust, and this again that the minimum Active Directory forest functional level for each forest must be Windows Server 2003. Raising the forest functional level to Microsoft Windows 2003 prohibits you from having or placing Microsoft Windows NT4 or Microsoft Windows 2000 Domain Controllers. This means that you cannot create linked mailboxes with a Windows 2000 forest in mixed mode.There is an abundance of documentation and discussion threads about this topic. See for instance:Problem Creating Exchange 2007 Linked Mailboxhttp://social.technet.microsoft.com/forums/en-US/exchangesvrdeploy/thread/46febaf3-ce1a-4162-9778-07bf79f7373eDeploying an Exchange Resource Forest (Part 1)http://www.msexchange.org/articles_tutorials/exchange-server-2007/planning-architecture/deploying-exchange-resource-forest-part1.htmlBut then read this:Although we recommend that you create a forest trust, you can create either a forest trust or an external trust. If you create an external trust, when you create linked mailboxes in Step 3, on the Master Account page of the New Mailbox wizard, you must specify a user account that can access the domain controller in the trusted forest. You can't use the credentials with which you are currently logged on. If you create linked mailboxes by using the New-Mailbox cmdlet, you must specify a user account that can access the domain controller in the trusted forest by using the LinkedCredential parameter. Deploy Exchange 2010 in an Exchange Resource Forest Topologyhttp://technet.microsoft.com/en-us/library/aa998031.aspx Here they state: an external trust ... I'm really not sure anymore. And I would be highly interested if it works with just an external trust to for instance Windows 2000 in mixed mode. MCTS: Messaging | MCSE: S+M | Small Business Specialist

I confirmed the two way trust is an external trust.In step 3, I can specify a user account, but when I click on Browse to select a "Trusted forest or domain:", all I see is "There are no objects to select" and "0 object(s) found."Any ideas on why the trusted domain does not show?Thanks,Ron.

Anyone have any ideas on this problem?Thanks,Ron.

I think the basic problem is that your Windows 2000 domain is operating in mixed mode. It should work in Windows 2000 native mode. Please note: This is nothing I know for sure, nor do the people I have discussed this matter with (mostly out of academic interest). It's more an educated guess. Changing the domain mode is irreversible, and you will not be able to use NT4 DCs:Understanding Function Levels in Windows Server 2003 Active Directoryhttp://www.petri.co.il/understanding_function_levels_in_windows_2003_ad.htm See for instance here:"The external trust will function between any two forests and the Exchange 2007 Linked mailbox implementation is fully operational when using a two way Windows external trust between any two forests ... Again the Exchange 2007 Linked mailbox implementation only requires a Windows 2000 forest functional level ..." Office Communications Server Resource - User Forest Topology http://communicationsserverteam.com/archive/2009/10/30/655.aspxIf you really need to create linked mailboxes with users in a Windows 2000 domain, you could start off testing this in a virtualized environment. Please let us know if it really works.MCTS: Messaging | MCSE: S+M | Small Business Specialist

Another solution could be that you have to check the option "Specify the mailbox database rather than using a database automatically selected:" in the dialog "Mailbox settings" while creating a linked-mailbox and select the appropiate mailbox-database. This also i you have only one exchange 2010 server and only one mailbox-database. Stephan

I confirm this one. Had the exact same problem. But after i selected a mailbox database in the previous page, the problems went away :|