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	25 (or 587)
Auth method	PLAIN
Username	any value (e.g. sandbox)
Password	your Pro API token (tm_pro_...)

TIP

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

Code examples

Node.js (Nodemailer)

const nodemailer = require("nodemailer");

const transporter = nodemailer.createTransport({
  host: "smtp.mail.td",
  port: 25,
  auth: {
    user: "sandbox",
    pass: process.env.MAILTD_TOKEN, // tm_pro_...
  },
});

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", 25) 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:25", 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       = 25;

$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", 25, "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", "25");
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=25
MAIL_USERNAME=sandbox
MAIL_PASSWORD=tm_pro_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 = 25
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: 25,
  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=25
export SMTP_USER=sandbox
export SMTP_PASS=tm_pro_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

Ensure your network allows outbound connections on port 25. Some cloud providers (AWS, GCP) block port 25 by default. Try port 587 as an alternative.

Authentication failed (535)

• Verify the token starts with tm_pro_.
• 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.