Cannot send mail using SwiftMailer using SmtpTransport in a live environment, but can send to localhost

Question

I use SwiftMailer to send simple mail. But when I use the SmtpTransport method (with hostname, username and password), I get the following error when using 2 possible authenticators. I was looking for a problem in stackoverflow but could not find a solution.

Fatal error: Uncaught exception 'Swift_TransportException' with message 'Failed to authenticate on SMTP server with username "[e-mail]" using 2 possible authenticators' in /home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Transport/Esmtp/AuthHandler.php:181 Stack trace: #0 
/home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Transport/EsmtpTransport.php(307): Swift_Transport_Esmtp_AuthHandler->afterEhlo(Object(Swift_SmtpTransport)) #1 
/home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php(118): Swift_Transport_EsmtpTransport->_doHeloCommand() #2 
/home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Mailer.php(79): Swift_Transport_AbstractSmtpTransport->start() #3 
/home/yyyyyyyy/public_html/testmail.php(51): Swift_Mailer->send(Object(Swift_Message)) #4 {main} thrown in /home/lexington21/public_html/swiftmailer/lib/classes/Swift/Transport/Esmtp/AuthHandler.php on line 181

My source is as follows. This source works fine in my local host, but not when it loads into a live environment.

$transport = Swift_SmtpTransport::newInstance("SMTPHOST", 25)
->setUsername("user")
->setPassword("pass");

$mailer = Swift_Mailer::newInstance($transport);

$to = "[e-mail]";
$subject = "Test Mail";
$email_body = "Hi Please confirm if you have received this email.";

$mail = Swift_Message::newInstance($subject)
->setFrom(array("[e-mail]"))
->setTo(array($to))
->setBcc(array("[e-mail]", "[e-mail]"))
->setBody($email_body, 'text/html');

$mailing_result = $mailer->send($mail);

I used 465 with ssl but got this error.

Swift_SmtpTransport::newInstance("SMTPHOST", 465, 'ssl')

Error

Fatal error: Uncaught exception 'Swift_TransportException' with message 'Connection could not be established with host SMTPHOST [Connection refused #111]' in /home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php:265 Stack trace: #0 
/home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php(62): Swift_Transport_StreamBuffer->_establishSocketConnection() #1 
/home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php(113): Swift_Transport_StreamBuffer->initialize(Array) #2 
/home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Mailer.php(79): Swift_Transport_AbstractSmtpTransport->start() #3 
/home/yyyyyyyy/public_html/testmail.php(51): Swift_Mailer->send(Object(Swift_Message)) #4 {main} thrown in /home/yyyyyyyy/public_html/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php on line 265

Please help me solve this problem.

Answer 1

, "tls" "ssl" ( SMTP). , . "" Swiftmailer. , : localhost, SMTP- SMTP (Mailgun):

// $config is an array populated from a config file
$host = $config['host'];
$port = $config['port'] ?: 25;
$user = $config['user'];
$pass = $config['pass'];
$security = 'tls';
if (isset($config['security'])) {
    $security = $config['security'];
}
if (empty($config['security'])) {
    $security = 'tcp';
}

$transport = Swift_SmtpTransport::newInstance($host, $port, $security)
    ->setUsername($user)
    ->setPassword($pass);
// Explicitly set HELO domain
$transport->setLocalDomain($host);

$mailer = Swift_Mailer::newInstance($transport);