Followed up with contacting Mailjet.com yesterday about too many emails being "pre-blocked" by their system (all transactional emails, receipts, sign up email, completed test confirmations, etc).
Signed with with Mandrill.com just in case Mailjet fails to find a solution.
Updated system so that if the student logs out on the shopping cart, it will come back to the shopping cart when they re-login if they have not selected any of the shopping cart items. Previously it would take the student to a payment page for only the course fee upon re-login.
Set up two new computers, configuration and software