You also need to configure email schedule with a shorter value.

* Enable Developper mode.
* Parameter > Technical
* Settings > Automation > Scheduled Actions
* Mail: Email Queue Manager

regards,

Thanks for the answer Jaideep. I just go to the particular event setting and at the communication section I set it. But before that, we must create a new event template using events.registration action and there we can put the email address that wants to receive the notification.