Your thank you emails are sent to your buyers once they completed a purchase. By default the emails will be sent immediately after, but you can also delay the emails so that they are sent up to one week later.
If you want to change when you reminders are sent follow these steps:
1. login to your control panel.
2. Go to your settings tab.
3. Go to “General settings”, “send email…” and choose when to send the emails.
4. Save changes.