A customer received a 2nd abandoned cart email after they placed an order. Why is that?
In general, customers should not receive additional abandoned cart emails for a cart after they place an order. MageMail detects orders in a number of ways that other email tools don't - such as orders placed over the phone. Even though the order placed over the phone won't be technically linked to the abandoned cart, MageMail detects it based on their email address.
If you hear back from a customer saying that they received an abandoned cart email after having placed an order, here are a few possibilities:
1. They used a different email address or account to place the order. In this case there isn't really any way to associate the order to the cart. It's basically the same as an entirely separate customer placing the order.
2. They came back to the site after placing their order and added items to their cart. In this case, the other abandoned cart email is for a completely separate cart from the initial one that they placed an order from.