Turning the order confirmation into a campaignA confirmation stuffed with banners, upsells and a newsletter signup stops being a transactional message. That has a practical cost — the customer cannot find their order number — and a legal one: the transactional exemption under CAN-SPAM turns on the primary purpose of the message, and in the EU and UK the lawful basis for processing a purchase does not stretch to promotional content nobody agreed to. One modest, relevant recommendation at the bottom is fine. A second campaign is not.
Sending the delivery email on a timerGuessing that delivery happens on day three means a share of customers get 'it's arrived!' while tracking still says in transit. Trigger from the carrier's delivered status through your store integration. If you cannot get that event, send later than you think rather than earlier — a day behind reads as thoughtful, three days early reads as automated.
Asking for a review before they have used itA review request at day two gets you reviews about the packaging. Wait until there is something to review. The exception is a product with an immediate verdict — a meal, a ticket, a download — where day two is right and day ten is too late to recall.
Running the whole sequence for every orderThe fourth order in three months does not need the getting-started email again. Suppress customers who have been through the sequence within the window, and branch first-time buyers away from repeat ones. Repeat customers should get a shorter version, or the reorder email alone.
Letting it run when something has gone wrongA review request arriving in the middle of an open support ticket, or after a refund, is the fastest way to turn a fixable problem into a one-star review. Add exit conditions for refunds, returns and open tickets, and evaluate them before every send rather than only at entry.