The famous saying: "Know yourself!" probably best summarizes the first part of this chapter. Indeed, before seriously thinking of migrating, the first task is to precisely assess the existing tools and needs.

The profile of an organization is defined by its size, its geographic dispersion, and the type of population concerned by the migration. This is the first parameter on which the migration strategy depends. The second parameter is simply the type of the existing mail system. Last but not least, there are the needs for the messaging system. These needs cover both the features of the existing system, which should be preserved, and the expected improvements. Having identified these three sets of parameters, the selection of an appropriate strategy can proceed.

Needless to say, complex issues such as the migration of a messaging system cannot be captured in a simple algorithm that you can just "run." For this reason, this chapter chooses to define five clearly identified strategies and to retain only eight types of organization. The chapter concludes, logically, by proposing one or more strategies for each of those eight categories.