Form Notifications was created as an sample add-on, and is meant for demonstration purposes only. It should not be used for complex or important workflows.
The number of notifications this add-on produces are limited by the owner's available email quota; it will not send email notifications if the owner's daily email quota has been exceeded. Collaborators using this add-on on the same form will be able to adjust the notification settings, but will not be able to disable the notification triggers set by other collaborators.