HiWe are currently running Exchange 2003 SP2/2007 SP1 mixed. When we originally installed Exchange in our org, we chose the option that we still had non-Outlook 2007 clients in our environment.All clients are now OL 2007, and all mailboxes have been moved to Exchange 2007 servers, we only have a few test mailboxes left on Exchange 2003.I understand that, whereas previously in Exchange 2003, Free/Busy information was held in Public Folders, in an OL/Exch 2007 combo, this information is now held in the actual mailboxes and accessed via the CAS.Is there a command we need to run to make this happen, now that the last OL 2003 client has gone? Or is it automatic?

Automagic.http://msexchangeteam.com/archive/2006/10/23/429296.aspxWhat does Exchange 2007 Availability Service do?

Ok, thanks... Just to get this right in my head, can I ask one further question: Let's say I am running Exchange 2007/2003 mailbox servers. When I installed the Exchange servers, I chose the option that said I had both OL 2007 *and* 2003 clients. So, according to what I understand, this means that FB information for Exchange 2007/OL 2007 users is stored in both the user's mailbox and the FB Public Folders). Let's say I have User1 (who uses Outlook 2007) on an Exchange 2003 server. At the moment, all his FB information is stored in the FB Public Folder folder that is special for each Adminstrative Group in Exchange, but replicated everywhere. I then move his mailbox to Exchange 2007. You are saying that now his FB is held on both his mailbox *and* the PF on his Exchange 2007 mailbox server? Is there no informaion held on the FB public folder that previously hosted his FB info? Also, would be I be correct in saying that now other OL 2007 clients (provided the mailbox is located on 2007) use the FB in his mailbox, via the Availability service, to access his FB info? Only OL 2003 and OL 2007 clients not on Exchange 2007 will use the Public Folder (although I'm not sure which PF)?

Correct. 2007 and 2003 users on Exch 2003 will publish their free/busy info to the pf system free/busy folders ( that matches their legacyExchangeDN )Exchange/OUtlook 2007 users will publish their free/busy to the pf free/busy folderthat matches theirlegacyExchangeDN ( if it exists) and will also maintain free/busy in the free/busy system folder of their mailbox.

Thanks Andy, just two more questions if you don't mind:i) If User1 is on Outlook 2007/Exchange 2007, will Outlook check the availbility service to check User1's own FB information? Or will it only check the availability if User1 wants to schedule a meeting with User2, and so in this case User1's Outlook will check the availbility service for User2's FB information?ii) The Availability service seems to be reached by a URL. Does this mean that if IE settings are not correct (e.g. point to a faulty Proxy server), Calendar functionality is not available?

for 1) I dont there would be any need to check it's only free/busy since it has full access to the calendar. Remember free/busy is really a representation of the times a mailbox has appts, is busy , free etc... If the mailbox needs to check another mailbox, then the availibility service is invoked via the Client Access Server. The level at which you can view another user's appts is set by that user and the avail service then provides that back to the requesting mailbox.2) If you cant connect correctly to the Availibilty service by that URL then, yes, your calendaring ( and Out of Office )experience will suffer. more info:http://technet.microsoft.com/en-us/library/bb232134.aspxUnderstanding the Availability Service