I've been reading through some of the threads on here regarding resource forests, but everything seems to indicate trusts are needed. My company is segmenting our organization from one AD forest/domain to multiple account forests and one resource forest. We have the following requirements: NO Trusts Retain current SMTP addresses (from the outside looking in) Sync GAL and free/busy amongst all forests. Can I use a combination of Exchange 2010 w/ linked mailboxes, FIM, and Federation Gateway? Thoughts? Suggestions?

Hi, This should be possible with the combination of Active Directory federation services and Exchange 2010 linked mailboxes. Then you will need to create a federation trust. More information can be found here: http://technet.microsoft.com/en-us/library/dd335198.aspx and here http://technet.microsoft.com/en-us/library/ff601760.aspx Kind regards, Bart Timmermans KPN Consulting - Technical Consultant www.bart-timmermans.nl Mark as Answer, if it is answer for your Question. Vote as Helpful, if it is helpful to you.

Federation is the best option in your case...Gulab Prasad, MCITP: Exchange Server 2010 | MCITP: Exchange Server 2007 MCITP: Lync Server 2010 | MCITP: Windows Server 2008 My Blog | Z-Hire Employee Provisioning App

Federation is the best option in your case... Gulab Prasad, MCITP: Exchange Server 2010 | MCITP: Exchange Server 2007 MCITP: Lync Server 2010 | MCITP: Windows Server 2008 My Blog | Z-Hire Employee Provisioning App So, if all of the segmented forests/domains are .local, do I need to use Federation gateway or just configure federation services between the two forests? I'm new to Federation services so I appreciate the patience.

Hi, Id suggest you refer to the following Microsoft articles: Understanding Federation http://technet.microsoft.com/en-us/library/dd335047.aspx Federation trusts http://technet.microsoft.com/en-us/library/cc738707(v=ws.10).aspx Create a Federation Trust http://technet.microsoft.com/en-us/library/dd335198.aspx Hope it is helpful. Fiona Liao TechNet Community Support