--- include/managesieve.lib.php
+++ managesieve.lib.php 2009-12-21 02:18:21.000000000 +0100
@@ -535,7 +535,7 @@

     /* Loop through each allowed authentication type and see if the server allows the type */
     foreach(explode(" ", $this->auth_types) as $auth_type) {
-        if ($this->capabilities["auth"][$auth_type]) {
+        if ($this->capabilities["auth"][strtolower($auth_type)]) {
             /* We found an auth type that is allowed. */
             $this->auth_in_use = $auth_type;
         }