I am in the middle of migrating from a mixed Exchange 2003/2007 environment to 2010 (one CAS one Mailbox). The 2007 is the CAS and the 2003 server holds the mailboxes. Internally the 2007 server is called mail.domain.com and the 2010 is owa.domain.com. I have been able to change all of the URL's etc. so that now mail.domain.com is the 2010 server and owa.domain.com is the 2007 server, but I have one small problem. If I create a new MAPI profile and enter in the name of an employee who has a mailbox on the 2010 server, it is resolving to owa.domain.com, not mail.domain.com. I must be missing something. The CAS Array name is mail.domain.com, all of the proper URL'S are changed and working.