A logistics engagement we picked up had a daily email run that was breaking once or twice a week, always silently. The job was simple: each morning the client's order management system exported a CSV of customers whose shipments had just dispatched, dropped it to SFTP, and SFMC should import + send a tracking notification.
The broken part: the automation was scheduled at 8:00 AM every day. Most days the file arrived at 8:30 or 9:00. Half the time the automation ran with yesterday's file, half the time it ran and imported nothing. A thousand customers got the wrong tracking email.
The fix is the File Drop Starting Source.
File Drop vs Schedule
File Drop triggers the automation when a new file arrives in a specified SFTP folder, not on a clock. If the client uploads at 11am instead of 8am, the automation fires at 11am. If they upload at 2am, it runs at 2am. No dependency on fixed schedules.
