Mage_PayPal fix for versions prior to 1.4

gistfile1.diff

diff --git a/app/code/core/Mage/Paypal/Model/Standard.php b/app/code/core/Mage/Paypal/Model/Standard.php
index e77e3d8..e70efea 100644
--- a/app/code/core/Mage/Paypal/Model/Standard.php
+++ b/app/code/core/Mage/Paypal/Model/Standard.php
@@ -368,8 +368,16 @@ class Mage_Paypal_Model_Standard extends Mage_Payment_Model_Method_Abstract
                 */
 
             } else {
-
-                if ($this->getIpnFormData('mc_gross')!=$order->getBaseGrandTotal()) {
+		$businessAccount = Mage::getStoreConfig('paypal/wps/business_account', $order->getStoreId());
+		$receiver = ($this->getIpnFormData('business') ? $this->getIpnFormData('business') : $this->getIpnFormData('receiver_email'));
+		if ($receiver != $businessAccount) {
+		    $order->addStatusToHistory(
+			$order->getStatus(),//continue setting current order status
+			Mage::helper('paypal')->__('Paypal IPN Invalid %s.', 'Invalid account')
+		    );
+		    $order->save();
+		}
+                else if ($this->getIpnFormData('mc_gross')!=$order->getBaseGrandTotal()) {
                     //when grand total does not equal, need to have some logic to take care
                     $order->addStatusToHistory(
                         $order->getStatus(),//continue setting current order status