I'm going to start a new post on this topic since so much has changed since my first post.In my lab, one Exchange 2003 server, two 2007 servers (one with mailbox and hub-transport and one with CAS only).Objective: Users will logon at the Exchange 2003 url, mail.mydomain.com. Exchange 2007 users will be re-directed to the 2007 OWA logonpage or even better right into their mailbox.Current behavior: The 2007 user when attempting logon at 2003 OWA receives an authentication pop-up for connecting to the mailbox server. (https://server01.mydomain.local/exchange). Once authenticated, the user is reirected to the 2007 OWA logon on the CAS server. If you chnge the IE settings to allow logon with current username and password, the user bypasses the first authentication box and is taken directly to the Exchange 2007 OWA logon page.My question is all of this or any of this correct behavior? Should the 2007 user be receiving the auth box for connecting to the mailbox server? Is there anyway the 2007 user who logs on at the 2003 OWA be passed all the way through to their mailbox?Thanks for any info

Since this is internal access then users can acess their mailbox by https://exchange2007servername/owa , unless I am missing something here no redirection is necessary internally. Now if they are trying to reach externally it will redirect automatically when the user authenticates.MVP Exchange Server

We will be migrating users from the 2003 box a little at a time. I don't want to have to inform a user everytime a mailbox is moved that they have a new OWA link. Everyone can continue to use the old link (mail.mydomain.com) until everyone is moved.I moved the CAS role off of my mailbox server and addded a new standalone CASjust for this redirection purpose. I solved this issue for domain member machines by making https://server01.mydomain.local/ (mailbox server) an intranet site through GP. That way the current user credentials are used to logon and it bypasses the extra logon box and goes directly to 2007 OWA logon page. This doesn't work for non-domain machines. So, on a non-domain machine you have to logon three times to get into a 2007 mailbox. If that's the way it has to work, I'm going to return to having the CAS role on my mailbox server.Any ideas?Thanks

Hi, I agree with John.Both Exchange 2003 and Exchange 2007 in the network, so you need to deploy Exchange 2007 CAS role if you want to use one URL to access mailbox both in Exchange 2003 and Exchange 2007. Besides, Id like to share one document about OWA 2003 and OWA 2007 coexistence. http://msexchangeteam.com/archive/2007/02/07/434523.aspx Regards, Xiu