The issues of operating system and operating environment are important when choosing a development environment and an environment for MAPI SDK installation. MAPI developers must be aware that these choices affect the operating system that their component will run on and the range of components that they will be able to target.
MAPI currently runs on the 32-bit environments provided with Windows NT and Windows 95, the native 16-bit environment of Windows 3.1 or later, and a 16-bit compatibility mode environment that allows 16-bit client applications to run on 32-bit platforms. Compatibility mode does not work for service providers.
The choice of development environment affects the environment that your component will be able to operate in. For service providers, the environment used for development is the only environment that their component will be able to operate in. That is, service providers developed in 16-bit environments can operate in 16-bit environments and service providers developed in 32-bit environments can operate in 32-bit environments.
Client applications are slightly more flexible. Clients written in 32-bit environments are like 32-bit service providers; they can only operate in 32-bit environments. Clients written in 16-bit environments, however, can operate in any environment.