Temporary email, programmatic

Create inboxes, read messages and pull OTPs over a simple REST API, or the typed SDKs on top of it. Point it at your own deployment with one config flag.

An inbox in one HTTP request

Authentication is a single API key header. One POST creates a real, deliverable address; a GET reads what has arrived in it. There is no mailbox provisioning step, no OAuth dance, and no waiting for a domain to warm up.

Every address is backed by real MX records on our own mail servers, so mail from anywhere on the internet reaches it the same way it would reach any other mailbox.

Addresses that outlive a single run

The address persists until you delete it, which matters more than it sounds. A script that registers an account somewhere can come back tomorrow and still receive that service's mail (password resets, renewal notices, whatever arrives later) instead of finding a dead address.

When you want a clean slate without losing the registration, there is an operation that empties every message and keeps the address. That distinction matters between test runs: deleting the address would force you to register again wherever you used it, while emptying it just gives the next run an inbox with nothing in it to confuse the assertions.

Sending, not only receiving

The same API sends mail from your inbox address, DKIM-signed through our own outbound servers. Replies stay in the original conversation with the threading headers filled in, and you can copy other recipients or attach files.

Outbound is queued rather than blocking, so a send returns as soon as it is accepted. Because "accepted" is not "delivered", there is a way to ask afterwards what happened to a specific message, and a webhook if you would rather be told than poll.

Read the details

curl -X POST https://mailflat.net/api/v1/inboxes \
  -H "X-API-Key: mf_live_..." \
  -d '{"label":"signup"}'
# → { "address": "signup-…@….mailflat.net" }

Frequently asked questions

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Ready to try it?

MailFlat for instant email inboxes for testing, automation & AI agents.