Automative email

You have to define an indocator, and generate email when date is passed.

MAnually send email.
You can define email templatre with data you want...

Hello

We do not directly offer an automation to notify the change of the planned end date.

But you could use event notifications.
Either on an activity or on a floating milestone that would move with the planning and asking to be notified of "any modification" or "modification of the result and the response", taking care of course to enter the new date in the result For example.

I save the ticket #7095 to add the modification of the validated and planned end dates !