-1.396  MISSING_DATE    Missing Date: header
-1.985  PYZOR_CHECK Similar message reported on Pyzor (http://pyzor.org)
https://pyzor.readthedocs.io/en/latest/

<?php
require_once "Mail.php";

$from = "Chris <myname@mydomain.com>";
$to = "Mail Tester <test-zjuq7@mail-tester.com>";
$subject = "Hey!";
$body = "Hi,nnHow are you?";

$host = "smtp.mydomain.com";
$port = "587";
$username = "myname";
$password = "mypassword";

$headers = array ('From' => $from,
    'To' => $to, 'Subject' => $subject,
    'Reply-To' => $from);

$params = array ('host' => $host,
    'port' => $port,
    'auth' => 'PLAIN', // Note 1
    'socket_options' => array('ssl' => array('verify_peer_name' => false, 'verify_peer' => false)), // Note 2
    'username' => $username,
    'password' => $password);

$smtp = Mail::factory ('smtp', $params);
$mail = $smtp->send($to, $headers, $body);

if (PEAR::isError($mail)) {
  echo("<p>" . $mail->getMessage() . "</p>");
} else {
  echo("<p>Email has been sent!</p>");
}
?>