fixture.email
Start trial

~/fixture.email git:(main) start-trial

Email testing, built for agents.

Spin up real inboxes, send and receive actual email, and assert on it in your end-to-end tests — an AI-native alternative to Mailosaur that your AI coding agent can wire up on its own.

Start 15-day trial Read the docs
  • Mailosaur alternative
  • Runs in your CI
  • AI-native
agent · starter-prompt 
# paste into your coding agent
Point your agent at the fixture.email MCP:
  1. read the docs to learn the API
  2. create a mailbox
  3. prove it with an internal test email ✓
  4. save a reusable email-testing skill
Claude Code · Cursor · Codex

~/fixture.email --unlocks

Stop mocking email. Test the real thing.

01

Real email, actually delivered

Send and receive genuine messages, not stubs. Assert on the exact subject, body, links, and headers your users receive.

02

Deterministic, never flaky

Every mailbox is uniquely addressable and isolated, so the same test passes the same way on every run. No shared state, no cross-talk, no retry-until-green.

03

Your agent does the wiring

Point your AI coding agent at the fixture.email MCP and it mints mailboxes and drafts the assertions against your suite. No SDK to learn, no dashboard to click.

~/fixture.email --how-it-works

From signup to passing test in one paste.

  1. 01 — Start your trial One checkout 15 days free, cancel anytime.
  2. 02 — Paste the starter prompt One paste Drop the one-paste prompt into Claude Code or any MCP-aware agent.
  3. 03 — Your agent builds Tests written for you It connects to fixture.email, mints mailboxes, and writes the email assertions straight into your tests.

~/fixture.email --plain-http

Simple HTTP. Your agent speaks it natively.

http · mint → send → assert 
# 1 — mint a mailbox
POST https://send.fixture.email/api/mailboxes
  → { "mailbox": "x7k2m9pqr3s4t5u6" }

# 2 — your app sends to  signup+x7k2m9pqr3s4t5u6@fixture.email

# 3 — assert it arrived
GET https://send.fixture.email/api/messages?mailbox=x7k2m9pqr3s4t5u6
  → 200 · subject "Verify your email" · 1 link  ✓

Or skip the HTTP entirely — your agent calls these through the MCP.

~/fixture.email --access-control

Access control, scoped to a single key.

Every key is org-scoped and hashed, and each one carries a precise grant — so the agent or CI job you hand a key gets exactly the access it needs, and nothing it doesn't. Mint scoped keys over the API or the MCP, not from a dashboard.

01

A grant per key

Tier × a named set of mailboxes × the Inbox / Sent / Tag message classes × List / Read / Delete actions — with sending folded in. Out-of-grant returns 404; an action it lacks returns 403.

02

Secrets the agent never sees

Author a scoped key over the API or the MCP, then reveal the raw secret once in the portal through an inert claim link. It never lands in a transcript, a tool result, or our logs.

03

Stable mailbox handles

Mailboxes carry unique-per-org labels, so a grant can name a set of mailboxes that stays meaningful as the underlying addresses rotate.

~/fixture.email --migrating

Everything you used Mailosaur for. Less of what you didn't.

Mailboxes, real send and receive, content and attachment assertions — the capability you already rely on. The difference is what is around it: no dashboard tax, and an agent that does the integration for you.

  • Real mailboxes, send & receive, assertions
  • Works in the CI you already run
  • Your agent writes the integration

~/fixture.email --about

Built for the agents that build with you.

fixture.email is end-to-end email testing for software teams and the AI agents that build with them: mint disposable mailboxes, send and receive real messages, and assert on the exact subject, body, links, and headers your users get. People and agents onboard the same way — get credentials and run a real email test in minutes. A developer signs up through checkout and pastes a starter prompt into their agent, and from there the agent drives the whole email-testing flow over the MCP, with no human in the loop.

~/fixture.email --pricing

One plan. Everything to test email, included.

Mint mailboxes, send, receive, and assert — over the full MCP server and the HTTP API, both on one X-API-Key. Internal test-domain sends, message reads, and mailbox / key / callback management don't draw on your send allowance — only delivery to real recipients outside your test domain is metered.

  • Programmatic mailboxes — send, receive, and assert on the real thing
  • The full MCP server and HTTP API on one X-API-Key
  • Internal sends, message reads, and mailbox / key / callback management — not metered

card up front · 15-day trial · cancel anytime before it ends

Only external recipients are metered — sends that leave your test domain. Scale that allowance with 1–99 units at checkout, adjustable anytime in the billing portal. Each unit raises your external-send allowance by 500/day and 15,000/month. The 15-day trial includes 50/day, 250 total external sends to try it end to end. Internal test-domain sends, reads, and management stay at plan cost.