Sometimes a customer might not receive their order confirmation email. This could be a delivery problem their end, or they may have mis-typed their email address.
The customer has mis-typed their email address, how do I change it?
Go to Commerce > Orders.
Find the order and click View.
Click on the Person, which will take you to their record under Contacts > People.
Click Edit (top right)
Change their Email address.
Click Update.
How do I re-send an order confirmation email to the customer?
Go to Commerce > Orders.
Find the order and click View.
Under More, click Re-send confirmation
An order confirmation email will have been sent to the customer.