You can resend a confirmation or receipt email by following these steps:
- Log in to your admin panel (yoursite.com/admin)
- Click Email > Sent Auto Responders in the sidebar
- Locate and select the relevant email (you can sort by name or date, or even filter by known information — see here)
- Click Resend at the top of the window
You will be presented with a pop up asking if you want to use the original template the email was sent with, or the latest template. This is relevant if the template was changed since the email was originally sent. Make your selection, and send.