I’m trying to replay an email with nodemailer in node.js, but I can’t.
It always generate a new thread instead of reply to the original email.

This is my code:

async function sendEmail(idMessage) {
    try {
        const transporter = nodemailer.createTransport({
            host: 'mail.test.es',
            port: 25,
            secure: false,
            ignoreTLS: true,
            auth: {
                user: process.env.EMAIL_USER,
                pass: process.env.EMAIL_PASSWORD,
            },
        });
       
        let mailOptions;
        if (idMessage) {
            console.log("idMessage:",idMessage)
            mailOptions = {
                from: process.env.EMAIL_USER,
                to: process.env.EMAIL_2,
                subject: 'test',
                html: `<p>Test:</p>`,
                inReplyTo: idMessage,
                references: `[${idMessage}]`,
            };
        }else{
            mailOptions = {
                from: process.env.EMAIL_USER,
                to: process.env.EMAIL_2,
                subject: 'test',
                html: `<p>Test:</p>`
            };
        }
        console.log("mailOptions",mailOptions)
        const info = await transporter.sendMail(mailOptions);
        console.log('Response:', info.response);
        console.log('info:', info);
        console.log('id:', info.messageId); 
    } catch (error) {
        console.log('Error', error);
    }
}

first I send an email without idMessage, and I get this:

mailOptions {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'test',
  html: '<p>Test:</p>'
}
Response: 250 OK id=1s7AyX-0000000Dhau-4Ab4
info: {
  accepted: [ '[email protected]' ],
  rejected: [],
  ehlo: [
    'STARTTLS',
    'SIZE 52428800',
    '8BITMIME',
    'AUTH PLAIN LOGIN',
    'SIZE 52428800',
    'HELP'
  ],
  envelopeTime: 202,
  messageTime: 110,
  messageSize: 280,
  response: '250 OK id=1s7AyX-0000000Dhau-4Ab4',
  envelope: { from: '[email protected]', to: [ '[email protected]' ] },
  messageId: '<[email protected]>'
}
id: <[email protected]>

At the moment is working well, but when I call the function with the messageId:

sendEmail('<[email protected]>');
I get this:

idMessage: <[email protected]>
mailOptions {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'test',
  html: '<p>Test:</p>',
  inReplyTo: '<[email protected]>',
  references: '[<[email protected]>]'
}
Response: 250 OK id=1s7B2d-0000000DiGI-2H7V
info: {
  accepted: [ '[email protected]' ],
  rejected: [],
  ehlo: [
    'STARTTLS',
    'SIZE 52428800',
    '8BITMIME',
    'AUTH PLAIN LOGIN',
    'SIZE 52428800',
    'HELP'
  ],
  envelopeTime: 208,
  messageTime: 112,
  messageSize: 409,
  response: '250 OK id=1s7B2d-0000000DiGI-2H7V',
  envelope: { from: '[email protected]', to: [ '[email protected]' ] },
  messageId: '<[email protected]>'
}
id: <[email protected]>

But is generating a new thread instead of a reply