Restrict user email on registration

[carefree2]

 $email = $_POST['email'];
$email = parse_url($email);
$email = $email['host']

if ($email == "yahoo.com" || $email == "hotmail.com"){

echo "The administrator has chosen not to accept email addresses from Yahoo and Hotmail";

echo "<a href=\"javascript:history.go(-1);\">
    <b><font size=\"2\">&lt;&lt; Previous page</font></b></a>";
exit();
}