Regarding SSL Protocol in SMTP server Validity - email

Question

I've success to sent a mail through PHP in last month with this code.
if($this->form_validation->run()){
#generate a random key
$key = md5(uniqid());
$this->load->model('model_users');
require_once "swift/lib/swift_required.php";
$transport = Swift_SmtpTransport::newInstance('smtp.gmail.com', 465, 'ssl')
->setUsername('xxxxx#gmail.com')
->setPassword('xxxxx');
// Create the Mailer using your created Transport
$mailer = Swift_Mailer::newInstance($transport);
$messagebody = "<p>Thank you for signing up!</p>";
$messagebody .="<form action= '".base_url()."main/register_user/$key' method='post'>
<input type='submit' value='Activate my Account'> </form> ";
// <p><a href='".base_url()."main/register_user/$key'>Click Here</a> to confirm your account.
// Create a message
$message = Swift_Message::newInstance('CBS Account Activation Message')
->setFrom(array('xxxxx#gmail.com' => 'CBS Group'))
->setContentType("text/html")
->setTo(array($this->input->post('email') => $this->input->post('email')))
->setBody($messagebody)
->setMaxLineLength(100)
;
// Send the message
$result = $mailer->send($message);
//send and email to user
if($this->model_users->add_temp_user($key)){
if($result){
echo "The email has been sent!";
$this->load->view('signup_success');
}
else{
// Failure Message
echo "Could not send mail";
}
}else
echo "Problem adding to database";
#add them to the temp_user db
}
Present I'm trying the use same code in same system it raises an error.
Fatal error: Uncaught exception 'Swift_TransportException' with message 'Connection could not be established with host smtp.gmail.com [ #0]' in C:\xampp\htdocs\code\application\controllers\swift\lib\classes\Swift\Transport\StreamBuffer.php:266 Stack trace: #0 C:\xampp\htdocs\code\application\controllers\swift\lib\classes\Swift\Transport\StreamBuffer.php(64): Swift_Transport_StreamBuffer->_establishSocketConnection() #1 C:\xampp\htdocs\code\application\controllers\swift\lib\classes\Swift\Transport\AbstractSmtpTransport.php(115): Swift_Transport_StreamBuffer->initialize(Array) #2 C:\xampp\htdocs\code\application\controllers\swift\lib\classes\Swift\Mailer.php(80): Swift_Transport_AbstractSmtpTransport->start() #3 C:\xampp\htdocs\code\application\controllers\main.php(370): Swift_Mailer->send(Object(Swift_Message)) #4 [internal function]: Main->forgot_validation() #5 C:\xampp\htdocs\code\system\core\CodeIgniter.php(359): call_user_func_array(Array, Array) #6 C:\xampp\htdocs\code\index.php(202): require_once('C:\\xampp\\htdocs. in C:\xampp\htdocs\code\application\controllers\swift\lib\classes\Swift\Transport\StreamBuffer.php on line 266
If i use this same code in another system it's run successfully and sent mail to particular mail id....
I didn't changed the code also.
How can i resolve this problem