Hi I need to migrate Exchange 2003 to Exchange 2007. The E2003 is a single Backend with no frontEnd server.The Exchange 2007willbe a single serverwith CAS/HUB/MBX/UC Iwant to maintain the same URL for client access becausemany of the usersare remote users and wewould not like to change the URLs on the Outlook anywhere profiles / ActiveSync profiles and OWA URL. This means that I need to change the "single point of contact" from the Exchange 2003 to somewhere else which will be able to redirect to the correct server, at least untill allmailboxes are located on the Exchange 2007 server. What should I do ? 1. Willsetting ISA server to publish theActiveSync //owa / RPCto the Exchange 2007(as it is a CAS server) willallow Exchange 2003 users to access their mailboxes using those services ? 2. Will installing a temporary CAS only server and publish it with ISA server will solve my problem for the duration of the migration ? 3. A few people suggested that the Edge transport role may have something to dowith redirecting clients to the correct server. Is there truth about it ? Can you point me to some info regarding such a solution ? Thanks

1: this will work somehow but not complete since CAS is located on the same box as MB role, in this case CAS cannot act as http proxy for Exchange 2003 servers 2: is the solution you have to do if the transition is going to take long time, if you can move all users in a short period of time and users allow for a short time of not having access to there mail you can go for number 1 3: Edge server has nothing to do with IIS, its only SMTP and there is no redirection functionality in SMTP.