What is email sandboxing?
A sandbox catches the mail your application sends before it reaches anyone real. That makes most template bugs cheap to find, and makes a few delivery bugs impossible to see.
Email Testing
Testing the email your application sends: OTP codes, password resets, receipts and webhooks, asserted in CI against a real inbox instead of a mock.
Powered by the Email Testing APIHow to test OTP verification end to end
A concrete recipe for OTP tests that do not flake: a real receivable address per test run, a long poll instead of a sleep, assertions on the mail itself, and CI wiring.
The best email testing tools, and which one your test suite actually needs
Mailpit, Ethereal, Mailtrap, Mailosaur, MailSlurp, Litmus and InboxDome do three different jobs. Pick the job first, then the tool, and know where each one stops.
Let your AI agent test email flows end to end
Claude Code, Cursor and any MCP client can create a real inbox, trigger your signup, read the OTP and assert on the email. No mocks, no manual copy-paste.
Testing email on your own domain
Point a domain you own at InboxDome so test inboxes read like real addresses on your brand. Verify ownership with a TXT record, then route the mail.
Testing email webhooks: verify the signature, then trust the payload
Get a push notification the moment mail arrives, verify the HMAC signature correctly, and avoid the raw-body bug that makes signature checks silently useless.
How to test a password reset email end to end
Drive a real password reset flow in a test: receive the mail, pull the reset link out of it, follow it, and set a new password. Without a mail server.
Test that your WooCommerce order emails actually arrive
WooCommerce order confirmations fail silently more often than any other transactional email. Check delivery, content and SPF/DKIM/DMARC, by hand or in CI.