Send email using the GMail SMTP server from a PHP page

I am trying to send an email via GMail's SMTP server from a PHP page, but I get this error:

authentication failure [SMTP: SMTP server does no support authentication (code: 250, response: mx.google.com at your service, [98.117.99.235] SIZE 35651584 8BITMIME STARTTLS ENHANCEDSTATUSCODES PIPELINING)]

Can anyone help? Here is my code:

require_once "Mail.php";

$from = "Sandra Sender ";
$to = "Ramona Recipient ";

$subject = "Hi!";
$body = "Hi,\n\nHow are you?";

$host = "smtp.gmail.com";
$port = "587";
$username = "testtest@gmail.com";
$password = "testtest";

$headers = array ('From' => $from,
  'To' => $to,

  'Subject' => $subject);
$smtp = Mail::factory('smtp',
  array ('host' => $host,
    'port' => $port,
    'auth' => true,
    'username' => $username,
    'password' => $password));

$mail = $smtp->send($to, $headers, $body);


if (PEAR::isError($mail)) {
  echo("
" . $mail->getMessage() . "
");
 } else {
  echo("
Message successfully sent!
");
 }
?>

Answer

// Pear Mail Library
require_once "Mail.php";


$from = '';
$to = '';
$subject = 'Hi!';
$body = "Hi,\n\nHow are you?";

$headers = array(
    'From' => $from,
    'To' => $to,
    'Subject' => $subject

);

$smtp = Mail::factory('smtp', array(
        'host' => 'ssl://smtp.gmail.com',
        'port' => '465',
        'auth' => true,
        'username' => 'johndoe@gmail.com',
        'password' => 'passwordxxx'
    ));


$mail = $smtp->send($to, $headers, $body);

if (PEAR::isError($mail)) {
    echo('
' . $mail->getMessage() . '
');
} else {
    echo('
Message successfully sent!
');
}