What is Priority Email Delivery?
For larger single scheduled, or one time webinar events. Suppose you have an event with 10k people registered for your webinar. Typically sending a reminder would rotate with other webinar users. In this case, the 10k webinar starts in 5 minute reminders, may exceed 5 minutes and arrive late with standard reminders.
A subscription with Priority Email Delivery, will automatically track and make sure that your emails are given Priority Delivery status and sent first ahead of others. Therefore, arriving on time.