using split() with wrong perl regexes will not work.

class/mime/Rfc822Header.class.php

@@ -656,7 +656,7 @@ class Rfc822Header {
      */
     function parsePriority($sValue) {
         // don't use function call inside array_shift.
-        $aValue = split('/\w/',trim($sValue));
+        $aValue = preg_split('/\s/',trim($sValue));
         $value = strtolower(array_shift($aValue));
 
         if ( is_numeric($value) ) {