Hey,
The reason is the email notification is tagged to failure of every activity.
So only if all activities fail ( act 1 AND act 2 AND '''') , would you get an email notification but based on the current flow, that email would not be triggered at any time.
Please follow the below blog for your resolution :
https://datasharkx.wordpress.com/2021/08/19/error-logging-and-the-art-of-avoiding-redundant-activities-in-azure-data-factory/