By default, the emails are sent to all the users who purchased on your shop.
However, you can decide to send them only to those users who consented to be contacted during the checkout process.
You need to enable the “Don’t email me checkbox” entry from the settings dashboard.
A checkbox is added to the “Checkout” page.
By refusing the consent, the users’ email addresses will be automatically inserted in the blocklist. In this way, the users won’t receive any email to encourage them to review the products they purchased.