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Mailtrap Email Sandbox
Catch and inspect outgoing email in a fake inbox so test sends never hit real people
Mailtrap Email Sandbox is a fake SMTP server plus API that captures every email your app sends in development, letting you inspect HTML, headers, spam score, and blacklist checks without delivering to real recipients. It has a forever-free tier and an API to programmatically read captured messages.
Free tier
Free forever sandbox: ~100 test emails/month on the basic tier, 1 inbox; unlimited API callsRate limits
Sandbox send is rate-limited (short bursts rejected with an error); exact RPS not publishedAuth
API keyBase URL
https://sandbox.api.mailtrap.ioWhat you'd build with it
- Safely test app email flows without spamming real inboxes
- Assert on email content/subject in CI by reading captured messages via API
- Check spam score and blacklist status of templates before going live
- Preview how an email renders across HTML/text without a real send
Key endpoints
- POST
/api/send/{inbox_id}Send a test email into a sandbox inbox via API - GET
/api/accounts/{account_id}/inboxes/{inbox_id}/messagesList captured messages in an inbox - GET
/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/body.htmlFetch the rendered HTML body of a captured message - GET
/api/accounts/{account_id}/inboxes/{inbox_id}/messages/{message_id}/spam_reportGet the SpamAssassin score for a captured message
Members
Members get the runnable recipe
Sign in free to copy the example request, see a sample response, and read the gotchas.
Tags
emailtestingsandboxsmtpqa