SMTP Configuration - Documentation

This guide covers how to configure your applications to use Mailloop's SMTP server for email testing.

SMTP Server Details

Use these settings to connect to Mailloop's SMTP server:

Host: smtp.mailloop.io

Port: 587 (STARTTLS) or 465 (SSL/TLS)

Authentication: Required

Username: Your sandbox username

Password: Your sandbox password

Security Options

STARTTLS (Port 587)

Recommended for most applications. The connection starts unencrypted and upgrades to TLS.

PYTHON

import smtplib
from email.mime.text import MIMEText

smtp = smtplib.SMTP('smtp.mailloop.io', 587)
smtp.starttls()
smtp.login('your-username', 'your-password')

SSL/TLS (Port 465)

Direct SSL/TLS connection from the start.

PYTHON

smtp = smtplib.SMTP_SSL('smtp.mailloop.io', 465)
smtp.login('your-username', 'your-password')

Environment Variables

Store your credentials securely using environment variables:

BASH

# .env
SMTP_HOST=smtp.mailloop.io
SMTP_PORT=587
SMTP_USER=your-sandbox-username
SMTP_PASS=your-sandbox-password

Then reference them in your application:

JAVASCRIPT

const nodemailer = require('nodemailer');

const transporter = nodemailer.createTransport({
  host: process.env.SMTP_HOST,
  port: process.env.SMTP_PORT,
  auth: {
    user: process.env.SMTP_USER,
    pass: process.env.SMTP_PASS
  }
});

Testing Your Configuration

Send a test email to verify your setup:

BASH

curl --url 'smtp://smtp.mailloop.io:587' \
  --ssl-reqd \
  --mail-from 'test@example.com' \
  --mail-rcpt 'recipient@example.com' \
  --user 'your-username:your-password' \
  -T message.txt

If configured correctly, the email will appear in your Mailloop inbox within seconds.

Common Issues

Authentication Failed

Verify your sandbox username and password are correct.

Connection Timeout

Check that your firewall allows outbound connections on port 587 or 465.

TLS Errors

Ensure your SMTP client supports STARTTLS or SSL/TLS connections.