Summary

Upgrades to Exchange 2007 require you to think carefully about your current Exchange organization and to identify any potential trouble spots. You must be aware of how you plan to get from your current legacy organization to the final goal of an all-Exchange 2007 organization. Are you going to use a transition strategy and upgrade the organization from within, allowing legacy Exchange and Exchange 2007 to coexist side by side for a time, or are you going to pursue the migration strategy and recreate your Exchange 2007 organization from scratch?

Whichever strategy you use, you must be aware of any special roles, applications, and add-ons you are using that will not be compatible with Exchange 2007. Although you can allow these legacy servers to be part of the organization for a while, keeping legacy servers around indefinitely may create more problems than it solves.