Question 1

What is an SMTP sandbox or mail trap?

Accepted Answer

An SMTP sandbox, also called a mail trap, is a fake mail server that accepts real outbound SMTP connections from your application but never delivers the messages to a real inbox. Instead, it captures each email so you can inspect exactly what your app sent, without any risk of a test message reaching a real customer.

Question 2

How is TempMailer different from just using a real inbox for testing?

Accepted Answer

A real inbox can't show you the raw HTML, headers, or how a message renders across devices, and there's always a risk of accidentally sending test traffic to a real person. TempMailer isolates every mailbox per credential, gives you device previews on desktop, tablet and mobile, raw HTML and header inspection, and a client-compatibility report, all without ever touching a real inbox.

Question 3

Can TempMailer send real email to Gmail, Outlook, or other providers?

Accepted Answer

No. TempMailer's SMTP catcher is a trap, not a mail relay. It authenticates and stores whatever is sent to it; it never forwards messages onward. Sending real, deliverable email needs a separate outbound path, such as your own mail server or a transactional relay, with proper SPF, DKIM and DMARC records for your sending domain.

Question 4

Does each mailbox get both SMTP and API access?

Accepted Answer

Yes. Every sandbox mailbox ships with real SMTP credentials for use in your app's mail configuration, plus a REST API key you can use like a transactional email API (post a sender, subject and HTML body) to drop a message straight into the mailbox, or to programmatically retrieve and delete received messages for automated test suites.

Question 5

Is my team's data isolated from other teams using the same TempMailer instance?

Accepted Answer

Yes. Every admin's workspace, including their users, mailboxes and mail, is scoped and checked on every request, with no shared access across tenants. Self-registered accounts stay pending until an administrator explicitly grants them a role.

Question 6

Do I need to install anything to use TempMailer?

Accepted Answer

No client install is required. Point your application's existing SMTP configuration at your TempMailer mailbox's host, port and credentials, and it will start capturing outbound mail immediately. Inspect everything from the web interface.

Question 7

Can AI agents and MCP tools read sandbox emails automatically?

Accepted Answer

Yes. Every mailbox includes an AI / MCP Connector link with a secure token. AI coding assistants, MCP tools, and automated test runners can call this endpoint to fetch the latest email in full body, retrieve OTP codes, search messages, or list today's mail without manual intervention.

Test outbound email without
touching a real inbox

Everything a mail sandbox should have

Isolated mailboxes

AI & MCP Connector

Device previews

Compatibility checker

SMTP + REST API

Tenant isolation

Team accounts

Temporary mail sharing

Synthetic test sender

How it works

Get a mailbox

Point your app at it

Send as usual

Inspect and iterate

Isolation you can trust

Frequently asked questions

Ready to stop testing in production inboxes?

Test outbound email without touching a real inbox