Your email provider is likely blocking our emails believing that they are spam. Check your spam folder to see if they are being filtered there instead of your inbox.
If you have an email account provided by Microsoft (Hotmail, Live, MSN, etc.), our emails may be blocked by Microsoft's servers. We recommend using a non-Microsoft email provider in order to insure that all emails are delivered successfully. You can setup a free Gmail account through Google that should have no issue receiving our receipt emails. You can even turn on email forwarding through Gmail so that all of the emails sent to the Gmail account are forwarded to an email address of your choosing.