SMTP Sandbox
for Developers
Capture every outgoing email from your application. Inspect HTML, headers, and attachments—without a single message reaching a real inbox.
Start Free — No credit cardWhat is an SMTP sandbox?
An SMTP sandbox is a controlled environment that intercepts outgoing emails from your application before they reach real recipients. Instead of delivering messages to actual inboxes, the sandbox captures them for inspection. You see exactly what your users would receive—without the risk of sending test data, broken templates, or debug content to real people.
SendPit provides a dedicated SMTP server that acts as this sandbox. Your application connects to it the same way it connects to any mail server—via standard SMTP protocol on port 587 with TLS encryption. The difference is that every email is captured, stored, and made available for review through a clean web interface.
No configuration changes to your email-sending code. No SDKs. No vendor lock-in. Just swap the SMTP host and start testing.
How it works
Three steps from zero to full email visibility. No dependencies to install, no code to change.
Create a mailbox
Sign up and create a mailbox in seconds. SendPit auto-generates encrypted SMTP credentials—a unique username prefixed with mb_ and a secure 32-character password. One mailbox per project, per environment, or per team member—however you want to organize.
Point your app at SendPit
Update your application's SMTP settings to use smtp.sendpit.com on port 587 with TLS encryption. Use the credentials from your mailbox. That's the entire integration—standard SMTP, compatible with every language, framework, and email library.
Emails captured, never delivered
Send emails from your application as you normally would. Every message is intercepted and stored in your mailbox. Open SendPit's web interface to view rendered HTML, raw source, headers, and attachments. Nothing reaches a real recipient.
Works with any SMTP client. No SDK required. No code changes beyond configuration.
Everything you need to test emails
SendPit's SMTP sandbox gives you full visibility into every email your application sends during development and testing.
Isolated mailboxes
Create separate mailboxes for each project, environment, or team. Staging emails never mix with development. Each mailbox has its own credentials and email store.
Encrypted credentials
Every mailbox gets auto-generated credentials—a unique mb_ prefixed username and a cryptographically secure 32-character password. Stored encrypted at rest.
Standard SMTP protocol
Works with any programming language, framework, or email library that speaks SMTP. Laravel, Django, Rails, Express, Spring—if it can send email, it works with SendPit.
HTML & source inspection
View emails as rendered HTML or dive into raw source code. Check that your templates look correct, links resolve properly, and dynamic content populates as expected.
Header analysis
Inspect every email header—From, To, Reply-To, Content-Type, MIME boundaries, and custom headers. Debug encoding issues, verify sender information, and validate RFC compliance.
Attachment handling
View and download email attachments. Verify that PDFs, images, CSVs, and other files are properly encoded, named correctly, and include the right MIME types.
Search & filtering
Find specific emails by subject, sender, recipient, or content. Filter by date range. When your mailbox has hundreds of test emails, search makes it manageable.
Credential rotation
Regenerate SMTP credentials instantly without deleting your mailbox or losing captured emails. Rotate passwords when team members leave or credentials are accidentally exposed.
Built for every stage of your workflow
From local development to staging to automated QA pipelines—SendPit fits wherever email testing happens.
Local development
Test email templates, transactional flows, and notification triggers without sending to real addresses. No more emailing yourself. No more accidentally spamming your coworker's inbox with test data.
- Preview HTML email rendering instantly
- Verify dynamic content and personalization
- Debug SMTP connection issues locally
Staging environments
Staging should mirror production—except for email delivery. Point your staging environment at SendPit so every email triggered by test users, seed data, and QA workflows is captured instead of delivered.
- Prevent accidental emails to real customers
- Validate email flows before production deploy
- Separate mailbox per staging instance
QA & automated testing
Run end-to-end tests that trigger emails—password resets, order confirmations, invitation flows—and verify the emails were sent correctly. Ideal for CI/CD pipelines where you need programmatic access to captured emails.
- Verify email content in test assertions
- Catch regressions in email templates
- Dedicated mailbox per test suite
Team collaboration
Share mailboxes across your team. Designers review email templates, developers debug SMTP issues, and QA verifies flows—all looking at the same captured emails in the same mailbox.
- Invite team members to shared mailboxes
- Organization-level access control
- Debug email issues together, not in isolation
Integrate in seconds
Update your SMTP configuration. That's the entire integration. Here are examples for popular frameworks.
Laravel (.env)
MAIL_MAILER=smtp
MAIL_HOST=smtp.sendpit.com
MAIL_PORT=587
MAIL_USERNAME=mb_your_username
MAIL_PASSWORD=your_32_char_password
MAIL_ENCRYPTION=tlsNode.js (Nodemailer)
const transporter = nodemailer.createTransport({
host: "smtp.sendpit.com",
port: 587,
secure: false,
auth: {
user: "mb_your_username",
pass: "your_32_char_password",
},
});Python (Django settings.py)
EMAIL_BACKEND = "django.core.mail.backends.smtp.EmailBackend"
EMAIL_HOST = "smtp.sendpit.com"
EMAIL_PORT = 587
EMAIL_USE_TLS = True
EMAIL_HOST_USER = "mb_your_username"
EMAIL_HOST_PASSWORD = "your_32_char_password"SendPit works with any SMTP client—Ruby, Java, Go, PHP, .NET, and more. If your framework supports SMTP configuration, it works with SendPit.
Why teams choose SendPit
You could disable email delivery in your application code. You could use your personal Gmail as a catch-all. You could pipe everything to /dev/null and call it a day.
But none of those approaches let you actually see what your users would receive. Disabling delivery means you cannot inspect the output. Using your own inbox mixes test emails with real ones and risks forwarding test data. Discarding emails gives you zero visibility.
SendPit sits in the middle—your application sends email exactly as it would in production, and SendPit captures every message for inspection. You get the full rendered HTML, all headers, every attachment, and the complete raw source. Nothing is lost, nothing is delivered.
It is the difference between hoping your emails work and knowing they do.
Start testing emails
in 30 seconds
Create a free account. Get SMTP credentials. Point your app at SendPit. Every email your application sends is captured and ready to inspect.
No credit card. No complex setup.
Just swap one SMTP host and start seeing your emails.
Free tier available. No credit card required. Setup takes under two minutes.