Notifications are queued the moment you perform a function, i.e., enroll someone in a class, assign a facilitator to a session, process the roster (which queues Learning Completion Notifications). Notifications stay in the queue until the next scheduled delivery - either 12:00 midnight or 12:00 noon.
If you've performed an E-Track function and delivery has not yet occurred, you can use Queued Notifications to see what notices have been generated and, if necessary, delete any notifications you do not want to be delivered.
Processed Notifications have already been delivered to end users. You can use Processed Notifications to verify if/when a trainer received notice of being assigned as the session facilitator, or to determine if a session attendee has received enrollment, survey, and learning completion notifications. You can also "Re-queue" a Processed Notification so that it will be re-delivered at the next scheduled delivery.