How do you implement Vercel's SSL in the code for email? Error: self-signed certificate in certificate chain

[Elindo586]

Summary

I recently change from Microsoft 365 Business Basics to Microsoft 365 Business Standard, and now contact forms in my website don't work anymore.

The code I have been using is:

export async function POST(req) {
  const transporter = nodemailer.createTransport({
    service: "Outlook365",
    auth: {
      user: process.env.EMAIL,
      pass: process.env.EPASSWORD,
    },
    
  });

^^ This was working awesome, until recently, now I get an error:

⨯ Error: self-signed certificate in certificate chain
    at TLSSocket.onConnectSecure (node:_tls_wrap:1679:34)
    at TLSSocket.emit (node:events:524:28)
    at TLSSocket._finishInit (node:_tls_wrap:1078:8)
    at ssl.onhandshakedone (node:_tls_wrap:864:12)
    at TLSWrap.callbackTrampoline (node:internal/async_hooks:130:17) {
  code: 'ESOCKET',
  command: 'CONN'
}
 POST /my/email-test 500 in 120ms

If I add this after user and pass it works, but this should be only for development.

tls: {
      rejectUnauthorized: false, // Allow self-signed certificates (development only)
    },

So? What do I do for production??? Apparently it should be something like this? but it isn't working:

export async function POST(req) {
  const transporter = nodemailer.createTransport({
    service: "Outlook365",
    auth: {
      user: process.env.EMAIL,
      pass: process.env.EPASSWORD,
    },
    
    tls: {
      rejectUnauthorized: true, 
      // ca: fs.readFileSync('path/to/your/self-signed-cert.pem'),  
      // since I don't have a file I copy and post it the SSL code given by Vercel.
      ca: process.env.SSLCERTIFICATE,
    },
  });

I got the SSL from here:

Additional information

No response

Example

No response

[icyJoseph]

Where did you get the certificate? from letsencrypt or something like that?

[Elindo586]

No, that is the SSL certificate from Vercel.

Look under:
https://vercel.com/account/domains/tu.biz

[Elindo586]

Has anybody else have problems with this?

I am trying to fix it with Microsoft, but their phone people basically only say to buy a new certificate from a trusted source, however, my emails were working just fine until recently with new Microsoft 365 Business Standard.

Are the SSL from Vercel not good enough for Microsoft Business Standard package?