I have a black box system that sends an email to confirm a scheduled task processing success. If the task fails for any reason there is no email sent. I am looking for a tool that would let me set up failure alerts. I need to program the tool when to expect the emails and if an expected email is not received, I need the tool to notify me somehow (email is fine). Does anyone have experience with preexisting software that could accomplish this?

Because the system is a black box I cannot edit the system for error handling. I have tried searching and asking colleagues but I have not been able to finding anything pre built to accomplish this at any price point.