Authenticated SMTP Relay

Route outbound emails from your development backend, framework, or Docker container to the Emailens sandbox SMTP server.

The Emailens SMTP Relay runs a dedicated SMTP gateway on port 2525 (with fallback port 587). It safely intercepts all outgoing mail from your application code and routes it into your dedicated sandbox inbox.

Emails routed through the relay are quarantined in your test environment. They never reach real mailboxes or external mail transfer agents.

SMTP Connection Details

Configure your mailer with the following parameters:

Parameter	Setting	Description
Host	`smtp.emailens.dev`	Global relay hostname
Port	`2525` or `587`	Port 2525 is unblocked by cloud providers (AWS, GCP, DigitalOcean)
Security	`STARTTLS`	TLS 1.2+ encryption enforced in transit
Username	`esmtp_...`	Dedicated credential username generated for your inbox
Password	`...`	Secret password generated for the credential

Framework Integration Examples

Node.js (Nodemailer)

import nodemailer from "nodemailer";

const transporter = nodemailer.createTransport({
  host: "smtp.emailens.dev",
  port: 2525,
  secure: false, // upgrades via STARTTLS
  requireTLS: true,
  auth: {
    user: process.env.EMAILENS_SMTP_USER, // e.g. esmtp_clx9abc123
    pass: process.env.EMAILENS_SMTP_PASS,
  },
});

await transporter.sendMail({
  from: '"Acme App" <auth@acme.com>',
  to: "user@example.com",
  subject: "Your one-time login code",
  html: "<p>Your code is <strong>482910</strong></p>",
});

PHP / Laravel

In your .env:

MAIL_MAILER=smtp
MAIL_HOST=smtp.emailens.dev
MAIL_PORT=2525
MAIL_USERNAME=esmtp_your_username
MAIL_PASSWORD=your_generated_password
MAIL_ENCRYPTION=tls
MAIL_FROM_ADDRESS="dev@myapp.local"
MAIL_FROM_NAME="${APP_NAME}"

In config/mail.php, Laravel defaults to STARTTLS when MAIL_ENCRYPTION=tls and MAIL_PORT=2525.

Python (`smtplib` & Django)

Using standard Python smtplib:

import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg.set_content("Your confirmation code is 882910")
msg["Subject"] = "Welcome to our platform"
msg["From"] = "system@myapp.com"
msg["To"] = "testuser@example.com"

with smtplib.SMTP("smtp.emailens.dev", 2525) as server:
    server.starttls()
    server.login("esmtp_your_username", "your_generated_password")
    server.send_message(msg)

In Django settings.py:

EMAIL_BACKEND = "django.core.mail.backends.smtp.EmailBackend"
EMAIL_HOST = "smtp.emailens.dev"
EMAIL_PORT = 2525
EMAIL_USE_TLS = True
EMAIL_HOST_USER = os.environ.get("EMAILENS_SMTP_USER")
EMAIL_HOST_PASSWORD = os.environ.get("EMAILENS_SMTP_PASS")

Ruby on Rails

In config/environments/development.rb:

config.action_mailer.delivery_method = :smtp
config.action_mailer.smtp_settings = {
  address:              'smtp.emailens.dev',
  port:                 2525,
  user_name:            ENV['EMAILENS_SMTP_USER'],
  password:             ENV['EMAILENS_SMTP_PASS'],
  authentication:       'plain',
  enable_starttls_auto: true
}

Go (`net/smtp`)

package main

import (
	"crypto/tls"
	"net/smtp"
)

func main() {
	auth := smtp.PlainAuth("", "esmtp_your_username", "your_password", "smtp.emailens.dev")
	to := []string{"test@example.com"}
	msg := []byte("To: test@example.com\r\nSubject: Test Email\r\n\r\nHello from Go!")

	err := smtp.SendMail("smtp.emailens.dev:2525", auth, "dev@example.com", to, msg)
	if err != nil {
		panic(err)
	}
}

Safe Delivery Guarantee

The Emailens SMTP relay acts as a dead-end sink:

Outbound delivery to external Mail Transfer Agents (MTAs) is impossible by architecture.
Any recipient address (e.g. billing@customer.com or ceo@realclient.com) will be safely routed into your staging inbox instead of escaping to the internet.
MIME payloads and attachments are parsed in-memory and committed to your isolated tenant database.

Authenticated SMTP Relay

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