In Limble, emails can be sent based on when a task if started, completed, or a certain number of days overdue. This notifications can be even more specific to the type of task and/or custom tags as well as priority levels.
These notifications have many uses. One example is to create escalation profiles. This is often used to notify a supervisor when a task is a certain number of days overdue. Multiple layers of notifications can be built to notify various people to ensure that a task is not forgotten.
This video explains how to set up this type of email notification.