html contact form doesn't recognise php file - php

Question

------THE CODE HAS BEEN MODIFIED SINCE FIRST POST------
For the life of me, I cannot get this to work. The page mentioned below will not recognise the email.php file in the root theme folder. I've tried everything!
Purpose: HTML contact form for a user to submit their details, PHP Script collects the users first name, last name and email address and in turn, redirects them to a thank you page.
Problem: HTML contact form displays fine, but when I click on "Okay, send me a voucher code!" it comes up with URL: http://charliesonlinestore.com/free-delivery-coupon-page/email.php with 'Nothing found', when it should be re-directing to a thank you page.
Here is the form code from HTML:
<div class="form">
<form method="post" name="landing-page" action="<?php echo get_template_directory_uri(); ?>/email.php">
First Name<br>
<input type="text" name="first_name"><br><br>
Last Name<br>
<input type="text" name="last_name"><br><br>
Email Address<br>
<input type="text" name="email"><br><br>
<input type="submit" name="submit" value="Okay, send me a voucher code!">
</form>
</div>
Here is my PHP Script code:
<?php
$first_name = $_POST['first_name'];
$last_name = $_POST['last_name'];
$email_from = $_POST['email'];
$to = 'charlie#charliesonlinestore.com';
$body = 'Here your email body text';
$subject = 'NEW Subscriber';
$headers = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'From: Lead Generator <Charlie#charliesonlinestore.com>' .
"\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
if($_POST['submit']){
if(mail($to, $subject, $headers)){
echo "mail send"; // change this later to your header location
}
else{
echo 'error sending mail';
}
}
else{
echo 'no post data';
}
?>
Confirmed points:
The email.php is in the root of the theme folder, storefront.
All items in the example are provided in the root folder, storefront.
When I tested this on local host (separate server), it worked fine and redirects without issues.
If you have any ideas on why this is happening then I would greatly appreciate it. I've almost completed my very own custom built contact form, lead generation and thank you page!
Just to note, I have checked previous posts and tried things such as putting a '/' infront of the PHP file name and also tried putting the file server address infront of the file name but to no avail.
Please help!

Answer 1

It tooks a little time before i saw it. The problem is your mail function. The php mail function needs a message before headers. And you replace your $header variable instead of extending it.
<?php
$name = $_POST['name'];
$email = $_POST['email'];
$to = 'charlie#charliesonlinestore.com';
$body = 'Here your email body text';
$subject = 'NEW Subscriber';
$headers = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'From: Your name <Charlie#charliesonlinestore.com>' . "\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";
if($_POST['submit']){
if(mail($to, $subject, $body, $headers)){
echo "mail send"; // change this later to your header location
}
else{
echo 'error sending mail';
}
}
else{
echo 'no post data';
}
?>