SMTP Setup

Configure your application to send emails through the Mail.td sandbox. Only SMTP credentials change — your application code stays the same.

Credentials

Setting	Value
Host	smtp.mail.td
Port	587 (recommended) — also supports 25, 465, 2525
Auth method	PLAIN
Username	any value (e.g. sandbox)
Password	your Pro API token (td_...)

TIP

Create an API token in Pro Dashboard → API Tokens. Use the full token string (starting with td_) as the SMTP password.

Code examples

Node.js (Nodemailer)

const nodemailer = require("nodemailer");

const transporter = nodemailer.createTransport({
  host: "smtp.mail.td",
  port: 587,
  auth: {
    user: "sandbox",
    pass: process.env.MAILTD_TOKEN, // td_...
  },
});

await transporter.sendMail({
  from: "dev@yourapp.com",
  to: "user@example.com",
  subject: "Welcome to MyApp",
  html: "<h1>Hello!</h1><p>Thanks for signing up.</p>",
});

Python (smtplib)

import smtplib
from email.mime.text import MIMEText
import os

msg = MIMEText("<h1>Hello!</h1><p>Thanks for signing up.</p>", "html")
msg["Subject"] = "Welcome to MyApp"
msg["From"] = "dev@yourapp.com"
msg["To"] = "user@example.com"

with smtplib.SMTP("smtp.mail.td", 587) as server:
    server.login("sandbox", os.environ["MAILTD_TOKEN"])
    server.send_message(msg)

Go (net/smtp)

package main

import (
    "net/smtp"
    "os"
)

func main() {
    auth := smtp.PlainAuth("", "sandbox", os.Getenv("MAILTD_TOKEN"), "smtp.mail.td")

    msg := []byte("From: dev@yourapp.com\r\n" +
        "To: user@example.com\r\n" +
        "Subject: Welcome to MyApp\r\n" +
        "Content-Type: text/html\r\n\r\n" +
        "<h1>Hello!</h1><p>Thanks for signing up.</p>")

    smtp.SendMail("smtp.mail.td:587", auth, "dev@yourapp.com",
        []string{"user@example.com"}, msg)
}

PHP (PHPMailer)

use PHPMailer\PHPMailer\PHPMailer;

$mail = new PHPMailer(true);
$mail->isSMTP();
$mail->Host       = 'smtp.mail.td';
$mail->SMTPAuth   = true;
$mail->Username   = 'sandbox';
$mail->Password   = getenv('MAILTD_TOKEN');
$mail->Port       = 587;

$mail->setFrom('dev@yourapp.com');
$mail->addAddress('user@example.com');
$mail->Subject = 'Welcome to MyApp';
$mail->isHTML(true);
$mail->Body = '<h1>Hello!</h1><p>Thanks for signing up.</p>';

$mail->send();

Ruby (Net::SMTP)

require "net/smtp"

message = <<~MSG
  From: dev@yourapp.com
  To: user@example.com
  Subject: Welcome to MyApp
  Content-Type: text/html

  <h1>Hello!</h1><p>Thanks for signing up.</p>
MSG

Net::SMTP.start("smtp.mail.td", 587, "localhost", "sandbox",
                ENV["MAILTD_TOKEN"], :plain) do |smtp|
  smtp.send_message(message, "dev@yourapp.com", ["user@example.com"])
end

Java (Jakarta Mail)

Properties props = new Properties();
props.put("mail.smtp.host", "smtp.mail.td");
props.put("mail.smtp.port", "587");
props.put("mail.smtp.auth", "true");

Session session = Session.getInstance(props, new Authenticator() {
    protected PasswordAuthentication getPasswordAuthentication() {
        return new PasswordAuthentication("sandbox",
            System.getenv("MAILTD_TOKEN"));
    }
});

Message msg = new MimeMessage(session);
msg.setFrom(new InternetAddress("dev@yourapp.com"));
msg.setRecipients(Message.RecipientType.TO,
    InternetAddress.parse("user@example.com"));
msg.setSubject("Welcome to MyApp");
msg.setContent("<h1>Hello!</h1><p>Thanks for signing up.</p>", "text/html");

Transport.send(msg);

Framework configuration

Laravel (.env)

MAIL_MAILER=smtp
MAIL_HOST=smtp.mail.td
MAIL_PORT=587
MAIL_USERNAME=sandbox
MAIL_PASSWORD=td_your_token_here
MAIL_FROM_ADDRESS=dev@yourapp.com

Django (settings.py)

EMAIL_BACKEND = "django.core.mail.backends.smtp.EmailBackend"
EMAIL_HOST = "smtp.mail.td"
EMAIL_PORT = 587
EMAIL_HOST_USER = "sandbox"
EMAIL_HOST_PASSWORD = os.environ["MAILTD_TOKEN"]

Rails (config/environments/development.rb)

config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  address: "smtp.mail.td",
  port: 587,
  user_name: "sandbox",
  password: ENV["MAILTD_TOKEN"],
  authentication: :plain,
}

Environment variables

We recommend using environment variables to switch between sandbox (dev) and production SMTP:

# Development / CI
export SMTP_HOST=smtp.mail.td
export SMTP_PORT=587
export SMTP_USER=sandbox
export SMTP_PASS=td_your_token_here

# Production
export SMTP_HOST=smtp.sendgrid.net
export SMTP_PORT=587
export SMTP_USER=apikey
export SMTP_PASS=SG.your_sendgrid_key

Your application reads these variables and the same code works in both environments.

Troubleshooting

Connection refused

If port 587 is not available, try one of the alternative ports:

Port	When to use
587	Default, works on most networks
2525	Alternative when 587 is blocked
465	Use for implicit TLS connections
25	Standard SMTP, but blocked by many cloud providers

Authentication failed (535)

• Verify the token starts with td_.
• Check the token hasn't been revoked in Pro Dashboard → API Tokens.
• Ensure your Pro subscription is active (not downgraded).

Emails not appearing in dashboard

• Confirm you received 250 OK after the DATA command.
• Check the SMTP Sandbox page in Pro Dashboard — emails appear within seconds.
• If using a library that pools connections, ensure the AUTH happens on each new connection.