Usability guidelines about e-commerce say that in an e-commerce platform, guest checkout is a must. Not providing this alienates any customer who just wants to get in and out.
What would you do in this situation? Do you force users to register before placing an order or do you ask for registration after the order has been placed? And what if the user closes the browser on the thank you page (likely the page where you ask for registration)?
Personally, I'd create an account during the order process, when users have to fill in data about payment and arrival time in restaurant (in this case). So, users fill in forms about their data (email, password, mobile phone, name and surname) and then they place the order. In this way the registration process is embedded in the order process and is not in another page which drives off the user from his goal.
But, there's a problem. What if the email provided is not valid? How will the user receive important communications? Asking them to register before the checkout forces the user to check his email to confirm the registration and then proceed to checkout.
I need your feedback on this scenario, but I think asking for registration after the order has been placed could lead to the problems I describe above.
UPDATE
After the order has been placed this is sent to the restaurant that has to prepare meals for that time. I want to avoid a order's confirmation link sent to the user's email (because the user before placing the order checks it, so there already is a confirmation of my order) and I don't want to block the user's order (especially because the order is for a precise time) as long as they do not confirm their registration.