Heroku Port Nodemailer

Question

我正在尝试将nodemailer与已部署的Heroku应用程序一起使用，该应用程序具有在heroku中加载的所有配置变量。我使用了这个基本示例，并且能够在本地部署和发送电子邮件：

https://github.com/binhc/react-nodemailer

通过更改此代码：

    var transport = {
  host: 'smtp.gmail.com',
  auth: {
    user: creds.USER,
    pass: creds.PASS
  }
}

为：

var transporter = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    type: 'OAuth2',
    user: creds.user,
    clientId: creds.googleClientId,
    clientSecret: creds.googleClientSecret,
    refreshToken: creds.googleRefreshToken
  }
});

这是我在heroku中发送的错误：

xhr.js:178 OPTIONS http://localhost:3002/send 0 ()
dispatchXhrRequest @ xhr.js:178
xhrAdapter @ xhr.js:12
dispatchRequest @ dispatchRequest.js:59
Promise.then (async)
request @ Axios.js:51
wrap @ bind.js:9
Book._this.handleSubmit @ book.js:45
apply @ _apply.js:15
baseInvoke @ _baseInvoke.js:21
apply @ _apply.js:16
(anonymous) @ _overRest.js:32
(anonymous) @ Form.js:60
callCallback @ react-dom.development.js:100
invokeGuardedCallbackDev @ react-dom.development.js:138
invokeGuardedCallback @ react-dom.development.js:187
invokeGuardedCallbackAndCatchFirstError @ react-dom.development.js:201
executeDispatch @ react-dom.development.js:466
executeDispatchesInOrder @ react-dom.development.js:488
executeDispatchesAndRelease @ react-dom.development.js:586
executeDispatchesAndReleaseTopLevel @ react-dom.development.js:597
forEachAccumulated @ react-dom.development.js:567
runEventsInBatch @ react-dom.development.js:728
runExtractedEventsInBatch @ react-dom.development.js:737
handleTopLevel @ react-dom.development.js:4201
batchedUpdates @ react-dom.development.js:12537
batchedUpdates @ react-dom.development.js:1939
dispatchEvent @ react-dom.development.js:4282
interactiveUpdates @ react-dom.development.js:12592
interactiveUpdates @ react-dom.development.js:1958
dispatchInteractiveEvent @ react-dom.development.js:4259
createError.js:16 Uncaught (in promise) Error: Network Error
    at createError (createError.js:16)
    at XMLHttpRequest.handleError (xhr.js:87)

我不明白，因为我有这行代码：

var port = normalizePort(process.env.PORT || '3002');

端口是否应该自动更新为heroku设置的端口？