Manage recipients for Alert - Task Completed for Owner

Summary:

Is adding an external email ID as a recipient for the Alert - Task completed for the Owner a supportive feature?

Content (required):

Hello all,

I wanted to notify an external source(email id) as and when a pending worker completes a particular task. I have created a custom alert, hardcoded an external user's email as a recipient, modified Journey's task notification setting, and overridden the delivered alert template with a custom one. However, the external user never receives an email when a pending worker completes a task.

Is it a supportive feature to hardcode an external email as a recipient for an alert, or is BIP the only alternative possible?