We are consolidating 2 Windows 2003 AD Forests both with Exchange 2007 after a business merger. Our top Exchange requirement is Calendering/FreeBusy. One of the business units wants to maintain autonomy and has suggested using AD Federation Services to join the forests instead of migrating one forest into the other using ADMT. Can we have access to calendering and feebusy utilizing a Federated Forests solution?

Greetings,Are we talking about implementing Exchange 2010? I belive you need at least one Exchange 2010 CAS server in each organization to establish the federation. I'm not sure the AD side matters (if you need 2008 or not... I don't see that in the requirements so far). As for the abilities of Federation, free/busy and calendar sharing is what Federation is all about. Here is a TechNet link to the Overview: http://technet.microsoft.com/en-us/library/dd335047.aspxHere is what it says: "Information workers frequently need to collaborate with external recipients such as vendors, partners, and customers, and share their availability (free/busy) information, calendar, or contacts. Microsoft Exchange Server 2010 provides easy sharing of information with external recipients. Federation provides the underlying trust infrastructure to enable easy and secure sharing of information across Exchange organizations and in cross-premises organizations."Obviously there is a bit of work involved to get this up and running. Others on the forum may have some deeper info on the caveats to your specific scenario.J. Peter BruzzeseTriple-MCSE, MCT, MCITP: MessagingExclusivelyExchange.com

My mistake this is AD 2003 r2 with Exchange 2007 in both Forests. It is not EX2010!

Ok... well, I cannot speak from 100% experience on this one. However, I did some research and you try a cross forest trust with some messing around with the Availability service.Here is a paragraph I read: "In Exchange 2007, you could share calendar data with other Exchange 2007 organizations. Doing so meant that your CAS servers had to talk to their calendar servers, and the controls around it were not that granular. In order to do it, you either needed to establish a forest trust and grant permissions to the other forest’s CAS servers (to get detailed per-user free/busy information) or set up a separate user in your forest for the foreign forests to use (to get default per-org free/busy data). You also have to fiddle around with the Autodiscover service connection points and ensure that you’ve got pointers for the foreign Autodiscover SCPs in your own AD (and the foreign systems have yours). You also have to publish Autodiscover and EWS externally (which you have to do for Outlook Anywhere) and coordinate all your certificate CAs. While this doesn’t sound that bad, you have to do these steps for every single foreign organization you’re sharing with. That adds up, and it’s a poorly documented process " http://blogs.3sharp.com/deving/archive/2009/08/21/some-thoughts-on-fba-part-2.aspxIt points off to this topic about the Availability service. http://technet.microsoft.com/en-us/library/bb125182.aspxSo, there is some hope here.If you think I have answered your question... please click the little Answer button. ;-)J. Peter