Undefined array key

PHP
21

Now to code is like this:

<?php

if($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['en-us-kf-km'])):

	//All processing goes within this outer POST condition
	$issue = (isset($_POST['issue']) ? $_POST['issue'] : '');
	$full_name = (isset($_POST['full_name']) ? $_POST['full_name'] : '');
	$gender = (isset($_POST['gender']) ? $_POST['gender'] : '');
	$email = (isset($_POST['email']) ? $_POST['email'] : '');

endif;

In place of

if(isset($_POST['submit'])){
    $to = "auto@5starastrology.com"; // this is your Email address
    $from = $_POST['email']; // this is the sender's Email address
    $headers2 = "From:\r\n" . $to;

}

And, the error is same:

Undefined array key "email" in /home4/xxx.com/xxx.php on line 16