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Mock SMTP

Capture application email in an isolated test inbox. Messages stay here and are never delivered to real recipients.

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About Mock SMTP

Point your application at a private SMTP capture instead of sending test messages to real users. Each capture has its own credentials and shares the inbox message reader, code extraction and event waits.

When to use it

Check a signup email without delivering it to a real user.

Mock SMTP example
POST /api/smtp-inboxes?ttlSeconds=86400

Configure your SMTP client with the returned host, TLS port, username and password.
Send a test message, then GET /api/email-inboxes/{id}/messages with your workspace key.
The original recipient never receives the capture.

How to use it

  1. Create a workspace capture and save the SMTP host, port, username and password separately.
  2. Configure your mail client to use TLS and SMTP authentication, then send a test email.
  3. Inspect the captured subject, text and codes. Download expected attachments as untrusted files. Delete the capture to revoke credentials.

Limits & privacy

The operator must enable the TLS SMTP listener first. Captures last one day in the browser and accept at most 100 messages of 128 KiB each. Attachment content counts against workspace storage and is removed with messages or the capture. Downloads use private links valid for two minutes. Password rotation revokes old SMTP credentials; API access still requires the workspace key. The server never forwards SMTP recipients or delivers mail externally. No real receiving-domain configuration is needed for SMTP capture.

Use this tool from the API reference or connect through the SDK, CLI, SSH, or MCP. Hosted calls share your plan allowances.