Nodemailer google workspace 在开发中工作，但在生产中将电子邮件 go 发送到垃圾邮件

Question

I have a project that sends emails back to people which I deployed on heroku. The problem is that it works fine in dev but when it has been deployed emails go directly to the spam. What causes this? Do you need more information from my code to help me?

 const oAuth2Client = new OAuth2(
    MAILING_SERVICE_CLIENT_ID,
    MAILING_SERVICE_CLIENT_SECRET,
    OAUTH_PLAYGROUND
  );
  oAuth2Client.setCredentials({
    refresh_token: MAILING_SERVICE_REFRESH_TOKEN,
  });
  try{

    const  accessToken = await oAuth2Client.getAccessToken();
    
    const transporter = nodemailer.createTransport({
      service: "gmail",
      auth: {
        type: "OAuth2",
        user: SENDER_EMAIL_ADDRESS,
        clientId: MAILING_SERVICE_CLIENT_ID,
        clientSecret: MAILING_SERVICE_CLIENT_SECRET,
        refreshToken: MAILING_SERVICE_REFRESH_TOKEN,
        accessToken,
      },
    });
    await transporter.verify();
    await transporter.sendMail({ from, to, subject, html });
     

///


await sendEmail({
    to: SENDER_EMAIL_ADDRESS,
    subject: subject,
    html: content
});
await sendEmail({
    to: email,
    subject: subject,
    html: `Dear ${firstName},
    <p> Thank you for getting in touch

    </p>
    <p>Best Regards,</p>
    `

Answer 1

If you get something like this "This email has failed its domain's authentication requirements. It may be spoofed or improperly forwarded.".

No, it's nothing that you can do. You've probably emailed yourself with fake emails like "test@yahoo.com", try using your real email.

Answer 2

There is a multiple reasons why this can happen in my case the DKIM of my email api wasn't set up correctly and another things too you can find out the reason why it is not working by using www.mail-tester.com to see the rating of your email and the reasons for it too.