Fix wrong pref name

diff --git a/imp/docs/UPGRADING b/imp/docs/UPGRADING
index d5c24c9..ebd8d6c 100644 (file)
--- a/imp/docs/UPGRADING
+++ b/imp/docs/UPGRADING
@@ -165,7 +165,6 @@ The following preferences are no longer used and may be safely removed from
 your ``config/prefs.php`` file and your preferences backend::
 
    'disposition_request_delivery'
-   'disposition_send_mdn'
    'wrap_width'