Index: program/include/rcube_imap.php
===================================================================
--- program/include/rcube_imap.php	(revision 25e6a0f11043537e9ea2950398f916d4db96a235)
+++ program/include/rcube_imap.php	(revision 68070e448c6c8cd09faa75fd70ff11bfea764cc1)
@@ -122,4 +122,11 @@
     {
         $this->conn = new rcube_imap_generic();
+
+        // Set namespace and delimiter from session,
+        // so some methods would work before connection
+        if (isset($_SESSION['imap_namespace']))
+            $this->namespace = $_SESSION['imap_namespace'];
+        if (isset($_SESSION['imap_delimiter']))
+            $this->delimiter = $_SESSION['imap_delimiter'];
     }
 
@@ -550,10 +557,4 @@
     {
         if ($this->delimiter !== null && $this->namespace !== null) {
-            return;
-        }
-
-        if (isset($_SESSION['imap_namespace']) && isset($_SESSION['imap_delimiter'])) {
-            $this->namespace = $_SESSION['imap_namespace'];
-            $this->delimiter = $_SESSION['imap_delimiter'];
             return;
         }
@@ -3506,8 +3507,10 @@
             $mbox = $mailbox . $this->delimiter;
             foreach ($namespace as $ns) {
-                foreach ($ns as $item) {
-                    if ($item[0] === $mbox) {
-                        $options['is_root'] = true;
-                        break;
+                if (!empty($ns)) {
+                    foreach ($ns as $item) {
+                        if ($item[0] === $mbox) {
+                            $options['is_root'] = true;
+                            break;
+                        }
                     }
                 }