PHPMailer can't send via postfix - phpmailer

Question

I already setup postfix in my debian linux VPS.
I can send email via ssh console using postfix.
I can send email using PHPMailer using my gmail account.
I can receive email in my debian linux VPS account.
Then I want to send email using PHPMailer via Postfix using my debian linux vps account. But it's failed with log below.
SERVER -> CLIENT: <br>
CLIENT -> SERVER: EHLO android<br>
SERVER -> CLIENT: <br>
SMTP ERROR: EHLO command failed: <br>
SMTP NOTICE: EOF caught while checking if connected<br>
SMTP Error: Could not connect to SMTP host.<br>
How to send email using PHPMailer using postfix ? should i use sasl ?
My sendmail.php
$mail = new PHPMailer;
$mail->isSMTP();
$mail->Port = 587;
$mail->SMTPSecure = 'tls';
$mail->SMTPAuth = true;
$mail->Subject = 'hello postfix phpmailer';
$mail->msgHTML(file_get_contents('contentemail.html'), dirname(__FILE__));
$mail->Host = 'yyyy.zzzz.com';
$mail->Username = "xxxx";
$mail->setFrom('xxxx#yyyy.zzzz.com', 'Ceramah Islam');
$mail->addReplyTo('xxxx#yyyy.zzzz.com', 'Ceramah Islam');
$mail->Password = "aaaaaa";
$mail->addAddress('bbbb#gmail.com', 'bbbb');
$mail->send();

Answer 1

I think the problem is caused by the "snakeoil" certificate and private key that come with Postfix. The trick is not to verify them. Here is what I found worked:
$mail = new PHPMailer;
$mail->isSMTP();
$mail->Host = "localhost";
$mail->Port = 25;
$mail->SMTPSecure = "tls";
$mail->SMTPOptions = array
(
'ssl' => array
(
'verify_peer' => false,
'verify_peer_name' => false,
'allow_self_signed' => true
)
);
$mail->setFrom('server#example.org', 'My Server');
$mail->addAddress('user#example.com', 'My User');
$mail->Subject = 'Message from PHPMailer and Postfix';
$mail->Body = 'Whatever';
if ($mail->send())
// SMTP message send success
{
// Put success logic here
}
else
// SMTP message send failure
{
// Put failure logic here
}