hay i used this code
$to = "mial@live.com,mail@yahoo.com";
$subject = "Mini-mass Emailer";
$message = "<a href='#'>Hello World</a>";
$headers = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
$headers .= 'From: Your Name <me@mydomain.com>' . "\r\n";
$headers .= 'Bcc: {$to}' . "\r\n";
if(mail($to, $subject, $message, $headers)){
echo 'ok';
}
but see what is happend every user see the full list of the users