How 'contact us' works?And what is '405 not allowed'? How i solve this.

Question

I will make a contact us form.
but when I run it. browser dislplay '405 not allowed'.
this is my website "www.contact646.cf".

Answer 1

My back end is this.

<?php
$name= $POST['name'];
$visitor_email= $_POST['email'];
$message= $_POST['message'];

$email_from= '[e-mail]';
$email_subject= "new form submission";
$email_body= "user name: $name\n".
"user email: $visitor_email.\n".
"user message: $message.\n";

$to = "[e-mail]";
$headers = "form: $email_from\r\n";
$headers = "reply-to: $visitor_email \r\n";
mail($to,$email_subject,$email_body,$headers);
header("location: index.html");

?>

Answer 2

what's your back-ends?