Does it give out any error?
You should check also try echoing out $_POST['email'] just above the if(isset($)POST['email'] statement to check whether it has a value.
Have this at the top of your script:
PHP Code:
<?php
ob_start();
error_reporting(E_ALL);
ini_set('display_errors', '1');
?>
and this at the very bottom:
PHP Code:
<?php
ob_end_flush();
Then tell us what it displays.