Koenig, ошибка!
$req = mysql_query("SELECT * FROM `mail_konts` WHERE `id_user`='" . $user_id . "' AND `type`='1' WHERE `read`='1'
union
("SELECT * FROM `mail_konts` WHERE `id_user`='" . $user_id . "' AND `type`='1' WHERE `read`='2' ORDER BY `time` DESC LIMIT $start, $kmess");