I would really appreciate any comments on an upcoming migration to Exchange 2007. Thanks any insight you can offer. Existing Environment One Exchange 2003 server Less than 50 mailboxes Exchange backup running around 17 GB. Several External OWA Clients Several RPC over HTTP clients We do use public folders Several internal devices send unauthenticated email using the 03 servers internal IP address. One Blackberry Enterprise Server that has been updated with the most recent service pack. We use Postini for spam reduction. The public IP address on our firewall that corresponds to the email server will only accept connections from Postini IP addresses. Migration Steps Install Exchange 2007 on a new server in the same organization. Install most recent Exchange service pack and updates. Configure server as a mailbox server and a client access server. Let the server run for a couple of days to ensure reliability. Wait to point external (OWA) clients to this server. Install a new SSL certificate to be used for mail.mydomainname.com Point external firewall to the new exchange server for OWA access and Outlook Anywhere. Move over mailboxes in batches over a two week period Clients with mailboxes on the 03 server that hit the 07 client access server will be redirected to the appropriate server. Decommission 03 Server and remove from domain. Questions- Any BES interop issues? Does the Exchange 03 server need to have a publicly accessible IP address when the 07 server starts acting as a front end? Or does, 07 just route this traffic? What steps are required to remove the Exchange 03 server considering it was the only server in the organization?