I currently have an Exchange setup as follows: two Exchange 2003 servers clustered together set up as the current mailbox stores, one Exchange 2003 setup as a frontend, one Exchange 2007 set up as a frontend (was set up for testing by my predecessor, never really used intentionally), and now four Exchange 2010 servers - two mailboxes in a DAG and two with Hub/CAS. Everything seems to be working fine with one exception - Outlook 2007/2010 clients are still autodiscovering the test 2007 frontend and not the 2010 CAS array. I know this because there's an expired cert on the 2007 box so the client displays a cert error when you attempt to autocreate the outlook profile. From what I've read, there is an SCP (Service Connection Point) in AD that is pointing to the old server and it is getting returned first, causing Outlook to try it first. How can I prevent Outlook from even attempting to connect to this 2007 box from now on?

http://www.msexchange.org/articles_tutorials/exchange-server-2010/management-administration/exchange-autodiscover.html

When Outlook 2007 is installed on a domain joined workstation then the Outlook client will query Active Directory for the Autodiscover information. Active Directory will return a list of SCP’s and the Outlook client will automatically select the first SCP in this list. Using the information found in the SCP the Outlook client will contact the Client Access Server for its configuration information and the Outlook client will be configured automatically.