Introduction
What MailSandbox is and how it fits into your workflow
What is MailSandbox?

MailSandbox is a fake SMTP sandbox for the email your applications send. Instead of delivering messages to real inboxes, your staging and development environments send them to MailSandbox, where every message is captured so you can preview it, inspect it, and share it with clients for review.

It is built for agencies and teams: unlimited inboxes, a project per client, and shareable review links — so nobody ever accidentally emails a real customer from a test environment again.

A captured email open in MailSandbox, showing the HTML preview alongside the message list
A captured email in MailSandbox, ready to preview, inspect and share.
How it works
  1. Create a project (typically one per client or product) and add an inbox to it.
  2. Point your application at the inbox over SMTP, the API, or the WordPress plugin.
  3. Every email your app sends is captured in the inbox instead of being delivered.
  4. Preview how it renders, check it for HTML, spam and blacklist issues, and share it for approval.

New here? The Quickstart walks you through it end to end in a few minutes.

Key features
SMTP & API capture Catch email from any stack over SMTP or a simple API. HTML & responsive preview See exactly how an email renders on desktop, tablet and mobile. HTML compatibility check Find features unsupported in Gmail, Outlook, Apple Mail and more. Spam score analysis Catch spam triggers before you send for real. Shareable review links Send a secure test URL to clients — no account needed. Projects per client Keep every client's inboxes and email cleanly separated.
Next steps