One of our banking engagements had a daily automation that imported a file of customers due for payment reminders and emailed each one. Production-quality pipeline, running clean for months.
One morning the upstream source system had a bug. The file it exported contained 50 records instead of the usual ~10,000. Automation ran on schedule, imported the 50 rows, and sent reminders to those 50 customers. The other 9,950 never got their reminder and the client's collections team discovered the gap two days later, after the due date had passed on several accounts.
The send itself wasn't wrong. The input was wrong, and nothing in the automation noticed.
Verification Activity, the fix
Automation Studio has an Activity called Verification whose only job is: check a Data Extension's row count, and stop the automation if the count is outside an expected range.
