public function findSent(User $user, $executeQuery = true)
    {
        $dql = "
            SELECT um, m, u
            FROM Claroline\MessageBundle\Entity\UserMessage um
            JOIN um.user u
            JOIN um.message m
            WHERE u.id = {$user->getId()}
            AND um.isRemoved = false
            AND um.isSent = true
            ORDER BY m.date DESC
        ";
        $query = $this->_em->createQuery($dql);

        return $executeQuery ? $query->getResult() : $query;
    }