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?

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.