The Email Specification

The Email Specification is a platform-agnostic, sourced checklist of what reliable email does: message format, authentication, deliverability, accessible content, client-safe rendering, privacy, internationalisation, lifecycle handling, security, and machine-readable automation.

It follows the product architecture of The Website Specification, adapted to the entire email delivery and rendering chain.

Topic Markdown under src/content/spec/ generates:

• browsable HTML topic and category pages;
• an interactive checklist and Markdown download;
• per-topic Markdown alternates;
• category sitemaps, schema graph, schema map, RSS, and llms.txt;
• llms-full.txt and an OKF bundle;
• the Pagefind search index;
• a bundled manifest for the MCP and A2A Worker.

Requires Node.js 22.12 or newer.

npm install
npm run dev             # site: http://localhost:31337
npm run mcp:dev         # MCP Worker: http://localhost:31338
npm run build
npm run check
npm run mcp:typecheck
npm run mcp:dry-run

The stateless, read-only Worker exposes search, list_topics, get_topic, get_checklist, get_categories, and get_changes, plus an audit_email prompt. Its production endpoint is configured as https://mcp.specification.email/mcp.

1. Pick a category under src/content/spec/.
2. Copy an existing Markdown file.
3. Set title, summary, status, order, related slugs, and at least one authoritative source.
4. Use the standard sections: What it is, Why it matters, How to implement, Common mistakes, Verification.
5. Add a changelog entry for material additions or status changes.

Code is available under the MIT licence. Specification content is available under CC BY 4.0.