Nekromal,
<?php
if (isset($_POST['ank_mail']) && ($_POST['ank_mail']==null || preg_match('#^[A-z0-9-\._]+Удалён
{
$user['ank_mail']=$_POST['ank_mail'];
mysql_query("UPDATE `user` SET `ank_mail` = '".my_esc($user[ank_mail]."' WHERE `id` = '$user[id]' LIMIT 1"
;
}
else $err[]='Неверный E-mail';
?>