When creating a reminder, you can specify a recipient under Advanced settings in the Send notification on completion section who will be notified by e-mail after the task (reminder) has been completed.
You can specify one recipient or several people or groups as recipients.
The e-mail notifications are created and sent once a day at 9:00 p.m. (time zone: CET, Europe/Berlin).
If you find another time more suitable, please contact your administration.