The last parameter is the type of the existing mail system. The principal platforms available in the electronic messaging market today are:
Each platform can be hosted in two modes:
Both the mail platform and the hosting mode will dictate what tools should be used (see Chapter 14, Performing the Migration on that topic) and, all the more, the appropriate operating mode. In some cases, depending on the version and the existing configuration, it may be necessary to develop ad hoc software solutions, hence the importance of the experimentation phase (pilot project).