Email Fixture Lab: inspect an email file locally

Email debugging often starts with one saved message. Email Fixture Lab turns a local .eml file into a structural JSON report: MIME parts, attachment sizes, nested messages and the delivery-status fields a bounce reports.

Addresses become consistent aliases within each inspection. The report leaves out raw bodies, subjects, filenames and diagnostic text. Nothing is rendered, uploaded or sent. Hashes, sizes and relationships can still be sensitive, so review the output before sharing it.

Try the included example.

Requires Node.js 22.13 or newer. Extract the ZIP and run:

node email-fixture-lab.mjs inspect examples/bounce.eml

The same inspection is available through a local, read-only MCP tool. Setup instructions are in the README. No Cloudflare account, API key, sign-up or payment is needed.

A small beta, not a mail security scanner.

This is a bounded inspection tool, not a full MIME validator or malware scanner. Reported delivery-status fields are not proof that a message was delivered. Windows has not been tested. Start with the synthetic example, then use files you are authorized to inspect.

Original code is MIT licensed; bundled dependencies retain their licenses. Valen Systems is independent of Cloudflare.

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