Not just when coming back from the payment provider to the
payment validation route `/shop/payment/validate`.
Otherwise, if you do not come back from the payment provider
page, that you quit just after having paid but just before
being redirected to Odoo, you do not receive the email.
The change within the `sale` module, while this issue concerns
`website_sale` only, has been accepted because this is a mechanism
that could be used by other modules.
opw-644348