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MailMatter

Disposable inboxes for test pipelines and AI agents — real, receivable addresses you mint on demand and read over an API.

MailMatter gives your tests and agents real, receivable email addresses on demand. Address an inbox as a named test scenario — {handle}.signup@mailmatter.dev, {handle}.password-reset@mailmatter.dev — and read what arrives from a browser, a test suite over REST, or an agent over MCP. The inbox is hermetic by design: it never visits a link, never loads a remote image, and hands you the raw .eml bytes when a renderer would hide the bug.

Anonymous inboxes are free with no signup. The REST API works with an anonymous inbox’s secret; API keys and MCP need a free account; webhooks and named handles are paid — see pricing for the current tiers and limits.

Start

  • Quickstart — mint an inbox and read your first message with two curl commands.
  • Handles, scenarios, and secrets — the addressing model: what a handle is, why scenarios need no setup, and how reading is authorized.
  • The hermetic inbox — what the viewer refuses to do on your behalf, and why that makes email tests trustworthy.

Test with the API

  • Testing with MailMatter — an address per test case, a long-poll instead of a sleep loop, and parallel runs that can’t read each other’s mail.
  • REST API — the programmable surface, with auth, status codes, and response shapes.

Drive it from an agent

  • Connect an agent over MCP — point Claude Code, Cursor, or any MCP client at mailmatter.dev/mcp and give it the full test loop as tools.

Push instead of poll

Run it day to day

  • Manage handles — create generated or named handles, label them, empty them, and release them safely.
  • Invite your team — shared orgs, invite links, and what members can and cannot touch.

Can’t find an answer? Email team@mailmatter.dev.