PHPMailer身份验证失败

当我在工作中尝试使用windows server 2012上的PHPMailer使用SMTP发送报告电子邮件时，我收到了身份验证不成功的错误。

我正在使用域上的服务器管理员帐户。

我很确定密码是否正确。

检查以下代码：

require '../PHPMailerAutoload.php';
$mail = new PHPMailer;
$mail->isSMTP();
$mail->SMTPDebug = 2;
$mail->Debugoutput = 'html';
$mail->Host = 'mail.example.com';
$mail->Port = 25;
$mail->SMTPSecure = 'tls';
$mail->SMTPAuth = true;
$mail->Username = "username@example.com";
$mail->Password = "yourpassword";
$mail->setFrom('from@example.com', 'First Last');
$mail->addAddress('whoto@example.com', 'John Doe');
$mail->Subject = 'PHPMailer SMTP options test';
$mail->msgHTML($html_message);

我得到了以下回复：

SERVER -> CLIENT: 220 exchangeserverhost.com Microsoft ESMTP MAIL Service ready at Tue, 3 Nov 2015 22:19:26 +0300
CLIENT -> SERVER: EHLO exchangeserverhost.com
SERVER -> CLIENT: 250-exchangeserverhost.com Hello 
CLIENT -> SERVER: STARTTLS
SERVER -> CLIENT: 220 2.0.0 SMTP server ready
CLIENT -> SERVER: EHLO exchangeserverhost.com
SERVER -> CLIENT: 250-exchangeserverhost.com Hello 
CLIENT -> SERVER: AUTH LOGIN
SERVER -> CLIENT: 334 
CLIENT -> SERVER: 
SERVER -> CLIENT: 334 
CLIENT -> SERVER: ==
SERVER -> CLIENT: 535 5.7.3 Authentication unsuccessful
SMTP ERROR: Password command failed: 535 5.7.3 Authentication unsuccessful
SMTP Error: Could not authenticate.
CLIENT -> SERVER: QUIT
SERVER -> CLIENT: 221 2.0.0 Service closing transmission channel
SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting
Mailer Error: SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting