Order management system exists. Emails need to be sent based on the following events.
1) order confirmation
2) do you still want to sell your phone reminder (after 6 days, if not shipped)
3) weve received your phone (once it shows as delivered)
4) we've confirmed your phone and have issued payment (once payment issued/confirmed)
5) Are you happy with our service (3-4 days after payment confirmed)
6) Have any friends that want to sell iphones (2 weeks after payment confirmed)