--- files/patch-Mail_Queue.php	(nonexistent)
+++ files/patch-Mail_Queue.php	(working copy)
@@ -0,0 +1,11 @@ 
+--- Mail/Queue.php.orig	2016-12-15 17:08:51 UTC
++++ Mail/Queue.php
+@@ -587,7 +587,7 @@ class Mail_Queue extends PEAR
+      * @return  boolean   whether $value is an MAILQUEUE_ERROR
+      * @access public
+      */
+-    function isError($value)
++    static function isError($value)
+     {
+         return (is_object($value) && is_a($value, 'pear_error'));
+     }