The test and this chapter are slanted toward planning more than operations. Therefore, this chapter does not focus on step-by-step procedures. For additional information on step-by-step procedures, refer to the Exchange 2007 documentation from Microsoft.
Any messaging organization, including one with Exchange 2003 or older versions, will have a period of coexistence and will require careful planning for interoperability. If you do not plan for interoperability, message flow or supporting messaging services may not work between the various versions of Exchange or other messaging systems.
This section covers one of the most common coexistence situations: coexistence with a legacy Exchange organization, including 2000, 2003, or a combination of both. If you are still running or working with Exchange Server 5.5, all traces of Exchange Server 5.5 computers must be removed from the organization before Exchange 2007 can be installed and supported. Table 8.1 outlines which versions of Exchange can coexist with Exchange 2007.
Table 8.1. Supported Coexistence Scenarios with Exchange 2007
Coexistence with Exchange 2007
Exchange Server 5.5
Mixed 5.5, 2000, and 2003
Exchange 2000 Server
Exchange Server ...