CDO & MAPI Programming with Visual Basic:

Chapter 3. Simple MAPI

Simple MAPI is a set of 12 functions that were created to allow developers to access Microsoft Mail post offices programmatically. At the time the API was created, it was known simply as MAPI. This API was later superseded by the completely different and much richer Extended MAPI. At that time, the old API was renamed Simple MAPI, and today the name MAPI by itself refers to Extended MAPI. Incidentally, Simple MAPI has been rewritten to use MAPI (i.e., Extended MAPI) internally.

There is no reason to use Simple MAPI in new development. The MAPI ActiveX controls, explained in the next chapter, are a Simple MAPI wrapper that is far easier to use than the API itself. However, Simple MAPI remains available and documented in order to support existing applications that were written to use it. This chapter explains how Simple MAPI is used from Visual Basic. If you’re not maintaining Simple MAPI code, it’s perfectly safe to skip this chapter.

Accessing APIs from Visual Basic

API stands for Application Programming Interface. In general, an API is any documented methodology for a software application to make use of functionality provided by another software application. On the Windows platforms, this exposure of functionality historically has been provided as function libraries implemented in dll files (although this is changing). You may be familiar with the Windows API—a set of operating system services exposed as functions implemented in Windows operating system ...