Each Reference topic includes a Quick Info table that names the MAPI header file where the API element is defined. The MAPI header files that are commonly used by developers include:
| Header file | Description of contents |
|---|---|
| MAPI.H | Definitions of structures, constants, and error values for Simple MAPI |
| MAPICODE.H | Definitions of status codes for error values |
| MAPIDBG.H | Definitions of macros for debugging |
| MAPIDEFS.H | Definitions of commonly used event types, property types, flags, structures, interfaces |
| MAPIFORM.H | Definitions of forms elements |
| MAPIGUID.H | Definitions of GUIDs |
| MAPISPI.H | Definitions of flags and interfaces implemented by MAPI for service providers and message services |
| MAPITAGS.H | Definitions of property tags |
| MAPIUTIL.H | Definitions of utility interfaces and functions |
| MAPIVAL.H | Definitions of validation macros |
| MAPIX.H | Definitions of flags and interfaces implemented by MAPI for clients |