Line 773 to line 785 in my PaymentModule.php
I commented it like this:
// if (Validate::isEmail($this->context->customer->email))
// Mail::Send(
// (int)$order->id_lang,
// 'order_conf',
// Mail::l('Order confirmation', (int)$order->id_lang),
// $data,
// $this->context->customer->email,
// $this->context->customer->firstname.' '.$this->context->customer->lastname,
// null,
// null,
// $file_attachement,
// null, _PS_MAIL_DIR_, false, (int)$order->id_shop
// );
Hope this helps, it worked for me.