为什么使用PHPMailer + tls发送的电子邮件具有To地址隐藏

Question

我正在使用PHPMailer通过SMTP发送带有TLS加密的电子邮件。电子邮件发送正常并按预期收到。但由于某种原因，未显示每封电子邮件的收件人地址。我在这里做错了吗？

  $mailer = new PHPMailer;

  // header
  $mailer->IsHTML(true);
  $mailer->CharSet = "text/html; charset=UTF-8;";
  $mailer->WordWrap = 80;

  // protocol
  $mailer->isSMTP();                      // Set mailer to use SMTP
  $mailer->SMTPDebug = 0;
  $mailer->SMTPAuth = true;               // Enable SMTP authentication

  // credential
  $mailer->SMTPSecure = 'tls';            // Enable encryption
  $mailer->Host = $agent['host'];         
  $mailer->Port = $agent['port'];
  $mailer->Username = $agent['username']; // SMTP username
  $mailer->Password = $agent['password']; // SMTP password

  // setup different addresses
  $mailer->From = $agent['from'];
  $mailer->FromName = $agent['from_name'];
  $mailer->addAddress($to, $name);
  $mailer->addBCC($agent['bcc']);
  $mailer->SingleTo = true;                

  // content
  $mailer->Subject = $subject;
  $mailer->Body = $html; 
  $mailer->AltBody = $text;                

  // finally, send out the mail message
  if (!$mailer->Send()) {
    throw new Exception('[Mailer] error: ' . $mailer->ErrorInfo);
  }

  // clear all addresses and attachments for next loop
  $mailer->clearAddresses();