I wanted to report a problem matriculating (registering or enrolling) students into a course using csv files (batch procedure). This is the situation: on the plugin 'enrol_flatfile' when you activate any of the flags or parameters 'mailstudent', 'mailteachers' or 'mailadmins' to report to the users the new role that they have on a course, the batch process registers the first user in the file, and when it tryes to report the enrollment to that user through email, immediately fails and stop matriculating the rest of the users showing the next error message:

Could not load preference message_provider_course_flatfile_enrolment_loggedoff. Does the component and name you supplied to message_send() match a row in message_providers? Message providers must appear in the database so users can configure how they will be notified when they receive messages. !!!