TO , CC , BCC in PHP mail()

Using mail() function to send mail with to , cc and bcc

$to       = 'nate@wpfixxyz.com'; 

$from     = 'nate@yopmail.com'; 

$bcc      = 'alan@brogan.com'; 

$headers  = 'From:  ' . $_POST['firstname'] .' '.$_POST['lastname'].' <' . $from .'>' . " \r\n" ;

$headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";

$headers .= "Bcc: $bcc\r\n";

$mail = '  

    <table>

        <tr><th colspan="2">Appointment Registration</th></tr>

        <tr><td><strong>First Name</strong></td> <td>'.$_POST['firstname'].'</td> </tr>

    </table>';

 mail($to,'Appointment Registration',$mail,$headers);