The MAPI (Messaging Application Program Interface) 1.0 allows you to send email from inside applications on your computer. If the MAPI program interface becomes corrupted, your computer will display a variety of MAPI error messages and you may not be able to send mail from Microsoft Outlook or other programs. Use the built-in "Fixmapi.exe" utility on your computer to solve the problem by replacing the core MAPI file.
Launch the Windows search app, and then enter "Mapi32.dll" in the search field. Open the file's location folder.
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Right-click the "Mapi32.dll" file name, and then select "Rename."
Type "Mapi32.old" as the file name and press "Enter."
Search for the "fixmapi.exe" file, and then select and run this file from the search results screen. There may be no visible process occurring, but the "fixmapi.exe" program will create a new "Mapi32.dll" file. If a prompt window appears, follow the instructions to fix or recreate the MAPI core file.
Restart your computer and allow the operating system to load.
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.