Can't Send Email Via Google Api

Question

I want to send email messages from my web system for notifications, but railway.com blocks SMTP for the free and hobby plans. Since my web system is still under development, I can’t upgrade to the pro plan yet.

So, I followed the suggestion to use the Gmail API without SMTP. Here’s an example:

```ts
// setup OAuth2 client
const oAuth2Client = new google.auth.OAuth2(
  BOT_GOOGLE.id,
  BOT_GOOGLE.secret,
  "https://developers.google.com/oauthplayground"
);

// inject refresh token
oAuth2Client.setCredentials({
  refresh_token: BOT_EMAIL.refreshToken
});

// create transporter with OAuth2
async function createTransporter() {
  const accessToken = await oAuth2Client.getAccessToken();

return nodemailer.createTransport({
    service: "gmail",
    auth: {
      type: "OAuth2",
      user: BOT_EMAIL.user,
      clientId: BOT_GOOGLE.id,
      clientSecret: BOT_GOOGLE.secret,
      refreshToken: BOT_EMAIL.refreshToken,
      accessToken: accessToken.token ?? "",
    },
  });
}
```

It works fine when I test locally, but it doesn’t work on Railway.com.