Coexistence and Migration
The previous chapters were about installing a brand-new Exchange Server 2013 environment, a so-called green-field installation. While there’s nothing wrong with this, chances are you already have an older Exchange environment running in your organization. If this existing environment is based on Exchange Server 2007 or Exchange Server 2010, then it is possible to create a coexistence scenario into which the new Exchange Server 2013 can be installed, and you can gradually transition your mailboxes to Exchange Server 2013.
If your existing environment is based on Exchange Server 2003, however, then you’ll run ...