Index: program/include/rcube_imap.php
===================================================================
--- program/include/rcube_imap.php	(revision dfc79b341c4ae80fe3bae0c52cadee7c28a108fd)
+++ program/include/rcube_imap.php	(revision a561cd35b8eb4c91e634a590774b8d18ed5b8a4a)
@@ -2587,8 +2587,12 @@
         // make sure mailbox exists
         if ($to_mbox != 'INBOX' && !$this->mailbox_exists($to_mbox)) {
-            if (in_array($to_mbox, $this->default_folders))
-                $this->create_mailbox($to_mbox, true);
-            else
+            if (in_array($to_mbox, $this->default_folders)) {
+                if (!$this->create_mailbox($to_mbox, true)) {
+                    return false;
+                }
+            }
+            else {
                 return false;
+            }
         }
 
@@ -2668,8 +2672,12 @@
         // make sure mailbox exists
         if ($to_mbox != 'INBOX' && !$this->mailbox_exists($to_mbox)) {
-            if (in_array($to_mbox, $this->default_folders))
-                $this->create_mailbox($to_mbox, true);
-            else
+            if (in_array($to_mbox, $this->default_folders)) {
+                if (!$this->create_mailbox($to_mbox, true)) {
+                    return false;
+                }
+            }
+            else {
                 return false;
+            }
         }