1. Open the Start menu and type 'Mapi32.dll' into the search field.
2. Right-click the 'Mapi32.dll' file name and click 'Rename.'

3. Type in 'Mapi32.old' as the file name and press 'Enter.'
4. Click the 'Start' menu button and type 'fixmapi.exe' into the search field, then press 'Enter' to run the file. There may be no visible process occurring, but the 'fixmapi.exe' program will create a new 'Mapi32.dll' file. If a program window appears, follow the instructions to fix or recreate the MAPI core file.
5. Restart your computer and allow the operating system to load.
6. Launch your email client and click the 'Send Mail' or 'Send/Receive Mail' button. Successful sending of any mail in the program's outbox indicates that the MAPI core file has been fixed and the MAPI error has been resolved.