# Email testing

> Test inboxes, unlimited addresses, waiting without polling, full MIME and automatic OTP extraction.
> https://facteur.eu/en/product/email

## An inbox your tests can query

A dedicated SMTP server per inbox, an API that waits for the message on your behalf, and everything inside it already broken out.

## What the engine does

- **Unlimited addresses, none to create first** : Any address ending in the inbox domain lands there. You generate a unique address per test, with no API call and no risk of collision between parallel runs.
- **Blocking wait, no polling** : The API holds the connection open until a message matching your criteria arrives, with a timeout you set. Your tests no longer contain an arbitrary sleep, so they stop being flaky.
- **Full MIME** : HTML, text, complete headers, encoding. What arrived on port 25 is what you read.
- **Attachments, verifiable without downloading them** : Name, size and SHA-256 checksum of every attachment, kept apart from signature images. Compare the checksum against your local file to verify exact content, without transferring a single byte.
- **Automatic extraction** : OTP codes, links and buttons are pulled out of the body on arrival. No more brittle regex copied into every test suite.
- **Send, reply and forward** : Reply to a message, forward it to a verified external address, or send an email from an inbox address to test an inbound loop.
- **Custom domain** : Use your own domain rather than ours, when your tests depend on the recipient domain: spam filters, allow lists, personalisation.
- **Retention set per inbox** : From 1 to 60 days depending on your plan. In performance mode the content is never written to disk: we confirm reception and drop the message.
- **Isolation per team** : Each inbox has its own access list, quotas and API keys. Team A’s CI neither sees nor consumes team B’s.

## Two ways in

The REST API covers everything, and nothing needs installing to call it. That leaves the case where the message should wake you, rather than the other way round.

- **REST API** : An OpenAPI-documented API, with its public reference and its guides. Nothing to install: the waiting happens on the server and the extraction on reception, so a test calls the message search with no dependency at all. The Playwright and Cypress plugins are on npm, and installing them stays optional: they buy comfort, not capability. The Integrations page carries the address of each.
- **Webhooks** : Every message received can trigger an HMAC-signed HTTP call to your system, with retries and a delivery log.