The problem is your forms action.
to be successful using Universal Email, you need to an understanding of how forms work.
In your case the form tag:
<form action="https://www.PayPal.com/cgi-bin/webscr" method="post" name="checkout_PP_LI_Hid" target="_blank">
has the action set to post to paypal:
When the submit button is clicked, the form goes directly to the action page.
You cannot trigger Universal email to send the email from the confirm page in this scenario.
In reality, when using Paypal Payments standard as your gateway, you should not be using universal Email to send the receipt unless you configure an IPN page. The reason for this is that transactions using PayPal standard do not occur in real time.
with paypal standard, the user is passed over to the paypal site, they select their payment method, and confirm the transaction. If paypal accepts the payment method, the transaction is placed in a queue, and the user is returned to your success page.
At this point the transaction has not been processed and no funds have been transfered, it can take seconds, hours or even days for the transaction to go through. Paypal will send an email to the customer when the transaction has been processed to notify them of success or failure.
you can configure your payal account to make an IPN post to a page you set up on your site. On that page, you can use the IPN post to send an email using Universal Email. See the following page for information on paypals IPN: