Why aren't customers receiving order confirmation emails?
You will need to ensure you have correctly setup the call back URL for your payment gateway
. Once logged into your account go to settings and then payment processing from the left hand side, then select configure this payment method next to your accepted payment gateway. Scroll to the bottom of the page to the instructions you need to follow in your payment gateway account and check these steps have been followed within your payment gateway account.
This can also happen if customers close their browser prematurely when being returned to the Powershop order complete page, as the emails are triggered by the customers hitting this page after successful payment.