Simple Send Mail PHP from POST variables

sendmail.php

<?php

     $to = isset($_POST["to"])? $_POST["to"] : ''; // 'personne@example.com';
     $subject = isset($_POST["subject"])? $_POST["subject"] : ''; // 'le sujet';
     $message = isset($_POST["message"])? $_POST["message"] : ''; // 'Bonjour !';
     $headers = 'From: '.( isset($_POST["from"])? $_POST["from"] : '') .'\r\n' .  // 'From: webmaster@example.com' . "\r\n" .
     			'X-Mailer: PHP/' . phpversion();

     echo mail($to, $subject, $message, $headers);

?>

sendmail_json.php

<?php

     $_POST = json_decode(file_get_contents('php://input'), true);

     $to = isset($_POST["to"])? $_POST["to"] : ''; // 'personne@example.com';
     $subject = isset($_POST["subject"])? $_POST["subject"] : ''; // 'le sujet';
     $message = isset($_POST["message"])? $_POST["message"] : ''; // 'Bonjour !';
     $headers = 'From: '.( isset($_POST["from"])? $_POST["from"] : '') .'\r\n' .  // 'From: webmaster@example.com' . "\r\n" .
     			'X-Mailer: PHP/' . phpversion();

     echo mail($to, $subject, $message, $headers);
?>