Hi Vladislav and all lurkers,

I have found the Bug !!!!!!!

in rcube_imap.php private function _list_headers

if ($this->sort_field != 'default' &&

       $this->get_capability('sort') && ($msg_index = iil_C_Sort($this->conn, $mailbox, $this->sort_field, $this->skip_deleted ? 'UNDELETED' : '')))

       {

              // nothing more to do

              } else {

               $a_index = iil_C_FetchHeaderIndex($this->conn, $mailbox, "1:*", ($this->sort_field == 'default') ? '' : $this->sort_field, $this->skip_deleted);

                      if (empty($a_index))

                              return array();

                      asort($a_index); // ASC

                      $msg_index = array_keys($a_index);

      }

remove the line asort($a_index); // ASC

after this will works fine.

I think the Problem are the sorting of the new in messagelist pushed messages !!

I have long time testet and debug and now i think thats the solution. 

best Eric