Valid from List & Label 20
Should the attempt to send an email via MAPI or XMAPI fail while there is a running instance of Outlook and the error message "MAPI_E_FAILURE" appears the reason could be Outlook which is not running in the same user context as your application.
In most cases, one of the two applications has been started via the context menu entry "Run as administrator". Therefore check again to see if the email transmission can be carried out successfully if both applications are started with the same user.
IDKBTE000886 KBTE000886