Office 365 Deployment TechGuide
Moving to Office 365 can be a complex undertaking. It involves two main phases: managing access for the user from the on-premises system to using the cloud and then migrating data from these on-premises systems (employee email, files and contacts) to the cloud environment. Microsoft has tools that aid in migrating both data and user access, but they lack important features, require significant design considerations and present compromises in functionality. These tools are based on older technologies that are rooted in on-premises architectures. Finally, if the services delivered by these tools fail, users cannot access their data in Office 365.