Microsoft has included a wide range of applications and features in the Office 365 platform in addition to email, such as various security, archiving, collaboration, communication, encryption, authentication and other services. However, the primary communications and collaboration tool for most users – and the core of Office 365’s functionality – continues to be email. By any measure email is a challenging application – arguably the most challenging – to deploy, manage and secure. While Office 365 includes needed functionality to support the core email and collaboration capabilities of the platform, it will not meet all users’ and all organizations’ needs. Osterman Research’s in-depth analysis of the Office 365 platform indicates that there are limitations with these services that should be considered by decision makers who are either considering a migration to Office 365 or have already deployed it.