Add auto reply to php code for contact form - php

Question

When a user fills the form I receive the details via mail using my code. That seems to be working fine but my concern is how do I set auto mail reply in my code?
Whenever user submits the form he should get a automated reply like "Thanks for contacting" .
How do i achieve that?
<?php
if(isset($_POST['email'])) {
$email_to = "demo#xyz.com";
$email_subject = "Contact Form Details";
function died($error) {
echo "We are very sorry, but there were error(s) found with the form you submitted. ";
echo "These errors appear below.<br /><br />";
echo $error."<br /><br />";
echo "Please go back and fix these errors.<br /><br />";
die();
}
if(!isset($_POST['name']) ||
!isset($_POST['subject']) ||
!isset($_POST['email']) ||
!isset($_POST['phone']) ||
!isset($_POST['message'])) {
died('We are sorry, but there appears to be a problem with the form you submitted.');
}
$first_name = $_POST['name']; // required
$last_name = $_POST['subject']; // required
$email_from = $_POST['email']; // required
$telephone = $_POST['phone']; // not required
$comments = $_POST['message']; // required
$error_message = "";
$email_exp = '/^[A-Za-z0-9._%-]+#[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/';
if(!preg_match($email_exp,$email_from)) {
$error_message .= 'The Email Address you entered does not appear to be valid.<br />';
}
$string_exp = "/^[A-Za-z .'-]+$/";
if(!preg_match($string_exp,$first_name)) {
$error_message .= 'The First Name you entered does not appear to be valid.<br />';
}
if(!preg_match($string_exp,$last_name)) {
$error_message .= 'The Last Name you entered does not appear to be valid.<br />';
}
if(strlen($comments) < 2) {
$error_message .= 'The Comments you entered do not appear to be valid.<br />';
}
if(strlen($error_message) > 0) {
died($error_message);
}
$email_message = "Form details below.\n\n";
function clean_string($string) {
$bad = array("content-type","bcc:","to:","cc:","href");
return str_replace($bad,"",$string);
}
$email_message .= "First Name: ".clean_string($first_name)."\n";
$email_message .= "Subject: ".clean_string($last_name)."\n";
$email_message .= "Email: ".clean_string($email_from)."\n";
$email_message .= "Telephone: ".clean_string($telephone)."\n";
$email_message .= "Comments: ".clean_string($comments)."\n";
$headers = 'From: '.$email_from."\r\n".
'Reply-To: '.$email_from."\r\n" .
'X-Mailer: PHP/' . phpversion();
#mail($email_to, $email_subject, $email_message, $headers);
?>
Thank you for contacting me. I will be in touch with you very soon.
<?php
}
?>
Also how to reset the form after successful submit?
Even if this is not done its okay but auto reply is very important for me.

Answer 1

Just send a second email, one to you with details and one to the sender with auto response message.
//your existing code
$headers = 'From: '.$email_from."\r\n".
'Reply-To: '.$email_from."\r\n" .
'X-Mailer: PHP/' . phpversion();
#mail($email_to, $email_subject, $email_message, $headers);
//add this
$headers = 'From: '.$email_to."\r\n".
'Reply-To: '.$email_to."\r\n" .
'X-Mailer: PHP/' . phpversion();
#mail($email_from, "Thanks For reaching Out", "Auto Reply - Do Not Respond", $headers);