I'm looking for a command to run on each exchange server to get Free/Busy to work on three different forests and three different exchange orgs. There is a two way trust setup on all three forests. Please help!

Are your clients Outlook 2007+ or newer? If so you can do this fairly easily via add-availabilityaddressspace and also exporting your autodiscover records from each organisation into the other, you will also need to ensure that each forest has name resolution for the others and that they all trust the certificates deployed on the relevant CAS servers. If you have Outlook 2003 you need Exchange Server 2010 to acomplish this without using 3rd party tools to replicate the SCHEDULE+ FREE BUSY PF. Instructions if you have OL2007+ Run In the source forest Add-AvailabilityAddressSpace -ForestName "TargetSMTPnamespace.com" -AccessMethod PerUserFB -UseServiceAccount $true Run In the target forest Get-ClientAccessServer | Add-AdPermission -AccessRights ExtendedRight -ExtendedRights "ms-exch-epi-token-serialization" -User "Source Forest\Exchange Servers" Note: You must perform these steps in all forests for a multi-way configuration Configuring cross-forest Autodiscover $a = Get-Credential <Enter Administrator credentials in the remote forest when prompted> Export-AutoDiscoverConfig -DomainController <Local GC> -TargetForestDomainController <Target GC> -TargetForestCredential $a -MultipleExchangeDeployments $true I blogged about achieving cross forest availability and delegation here... http://blogs.technet.com/b/neiljohn/archive/2011/10/12/exchange-server-2010-cross-forest-delegation.aspx Neil.

Also see: How to Configure the Availability Service for Cross-Forest Topologies http://blogs.technet.com/b/exchange/archive/2011/03/04/3412075.aspx Configure the Availability Service for Cross-Forest Topologies http://technet.microsoft.com/en-us/library/bb125182.aspx Fiona Liao TechNet Community Support