When a customer is placing an order and paying by PayPal IPN everything works great, except the confirmation email.

The status of the order is updated with "PayPal status: Completed @ 03:07:17 Feb 15, 2009 PST..." which, in my opinion, means that there is nothing wrong with the communication between zen-cart and PayPal.

Confirmation from PayPal is sent to Customer and me.

Already checked http://www.zen-cart.com/wiki/index.php/PayPal

Zen-Car version used: 1.3.8a, fresh install.