How to pass header into the mail

To pass a header into an email, you can use the headers parameter when sending the email using a programming language or a library. Here are some examples:

Python (using smtplib and email libraries)

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

msg = MIMEMultipart()
msg['From'] = '[email protected]'
msg['To'] = '[email protected]'
msg['Subject'] = 'Test Email'

# Add a custom header
msg['X-Custom-Header'] = 'Hello, World!'

body = 'This is the email body.'
msg.attach(MIMEText(body, 'plain'))

server = smtplib.SMTP('smtp.example.com')
server.sendmail('[email protected]', '[email protected]', msg.as_string())
server.quit()

Java (using JavaMail API)

import javax.mail.Message;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;

Message msg = new MimeMessage(session);
msg.setFrom(new InternetAddress("[email protected]"));
msg.setRecipient(Message.RecipientType.TO, new InternetAddress("[email protected]"));
msg.setSubject("Test Email");

// Add a custom header
msg.addHeader("X-Custom-Header", "Hello, World!");

String body = "This is the email body.";
msg.setText(body);

Transport.send(msg);

Node.js (using nodemailer)

const nodemailer = require('nodemailer');

let transporter = nodemailer.createTransport({
  host: 'smtp.example.com',
  port: 587,
  secure: false, // or 'STARTTLS'
  auth: {
    user: '[email protected]',
    pass: 'your-password'
  }
});

let mailOptions = {
  from: '[email protected]',
  to: '[email protected]',
  subject: 'Test Email',
  text: 'This is the email body.',
  headers: {
    'X-Custom-Header': 'Hello, World!'
  }
};

transporter.sendMail(mailOptions, (error, info) => {
  if (error) {
    return console.log(error);
  }
  console.log('Email sent: ' + info.response);
});

In each example, the headers parameter is used to add a custom header to the email. The key is the name of the header (e.g. X-Custom-Header) and the value is the value of the header (e.g. Hello, World!).

Mail Knowledge

How to pass header into the mail