I got an email contact form page on my website, with the following php code:

PHP Code:
$email $_POST['email'];
$message $_POST['message'];
$formcontent=" From: $name \n Message: $message";
$recipient "elvis@presley.com";
$subject "Web Mail";
$mailheader "From: $email \r\n";
mail($recipient$subject$formcontent$mailheader) or die("Error!");
$url 'http://www.trusa...html#!/page_More';
'<META HTTP-EQUIV=Refresh CONTENT="0; URL='.$url.'">';

Now, it works just fine when sending, but my situation is that apparently people can just press the Send button even if they don't fill everything out.
Can anyone tell me what the code would be to have all fields required to be filled?