From the home screen of the Frontpoint App:
Tap on the Menu button
Tap on the Notifications sections.
Tap on the settings cog .
Tap on the + button to create a new notification and select Sensor Left Open from the list.
From here you can check the boxes next to any Door and Window Sensors that you would to receive notifications for.
Select the amount of time the sensor needs to be open before the notification is sent.
Tap on +Add Recipient to select which phone numbers, emails or push devices you would like to receive the notification. You can also use the During this time frame: section to limit by times of day or days of the week that you will receive the notifications.
Tap Save when done.