I am upgrading to exhchange server 2007 from exchange 2003, currently I have the following environment.exchange server running coexistance: 1) exchange server 2003 (orignal) running on windows server 2003 1) exchange server 2007 on windows server 2008 box with client access, OWA, outlook anywhere and management tools installed 1) exchagen server 2007 on windows server 2008 box with mailbox, hub transport, and management tools installedI have moved my mailbox from ex2003 to ex2007, and it worked as expected. I was hoping to just connect to the CAS server with all my clients and keep the mailbox on a separate box. When I installed this on in a fresh domain, I got an error that the mailbox server must have the hub transport server on the same box. (new forest)Now that I have instlled in my existing forest the exchange 2007 coexistance with exchange server 2003, I notice that when I connect to exchange 2007 with outlook 2007 it wants to connect directly to the mailbox server. I intended for all the traffic to go through the CAS to get to the mailbox server, but it does not appear to be the case. Is there any way to force the use of the CAS with outlook clients internally? did I miss something? it appears that the recieve connectros on the hub transport is responsible for all the client connections.Should I move the hub transport to the CAS server, and is that even possible?any sugestions?Thank you,M

In Exchange 2007, Outlook (MAPI) connects directly to the mailbox server. This is what you're seeing and is by design. The CAS is responsible for client connections that are not Outlook in MAPI mode, such as OWA, Outlook Anywhere, POP, IMAP, etc.In Exchange 2010, the CAS is responsible for all client connections including Outlook using MAPI.Neil Hobson, Exchange MVP

Thanks,what about the sending and receiving of email? is that also done through the hub transport?

Yes, transport servers do that.Neil Hobson, Exchange MVP