## lama

def sent_folder
  Message.all(:conditions => {:is_deleted => false,
              :thread_id  => self.sent_messages.all(:select => 'distinct thread_id').map(&:thread_id),
              :sender_id  => self.id},
              :group      => 'thread_id',
              :order      => 'created_at DESC')
end

## baru

def sent_folder
  self.sent_messages.all(:conditions => {:is_deleted => false},
                         :order      => 'created_at DESC')
end