Dead Letter MCP Server

Turn .eml email exports into clean, local, LLM-ready Markdown. dead-letter converts .eml email exports into clean Markdown with YAML front matter - threads split, signatures stripped, attachments extracted, calendars parsed. One file or ten thousand.

People who work with converter, digital preservation and email and want it reachable from Claude, Cursor, VS Code, or another MCP client. The project is written in Python.

VERIFIED ACTIVE

LAST COMMIT 2026-09-29 · ★ 8 · #19 OF 98 MAINTAINED EMAIL · VERIFIED 2026-09-30

NOASSERTION · Python servers · how we verify → /methodology

01 · Install Dead Letter

before you install - you'll need

The README does not document required environment variables for a basic install.

Claude Code

claude mcp add bigcactuslabs-dead-letter -- uvx dead-letter

Claude Desktop / Cursor / VS Code - add to config

{
  "mcpServers": {
    "bigcactuslabs-dead-letter": {
      "command": "uvx",
      "args": [
        "dead-letter"
      ]
    }
  }
}

Same JSON for Cursor. For VS Code, rename the top-level key from `mcpServers` to `servers`.

Using another client? Same JSON, different key

Claude Desktop · mcpServers

Cursor · mcpServers

VS Code · servers

Windsurf · mcpServers

Zed · context_servers

Cline · mcpServers

Roo Code · mcpServers

Continue · mcpServers

LibreChat · mcpServers

Gemini CLI · mcpServers

Codex CLI · mcp_servers

Full setup guides: every client.

02 · Evidence

Security posture

What to check before giving this server access to your agent - from the registry, GitHub, and our own probes. We don't score safety; we show what's verifiable.

runs as local process (stdio) - runs on your machine with your user's permissions · container (OCI image) - can be sandboxed away from your filesystem · Claude Desktop extension (.mcpb bundle)

license no standard license detected - usage rights unclear; check the repo before commercial use

pypi package dead-letter - check the name against the project README before installing (PyPI has no namespace ownership)

registry namespace io.github.BigCactusLabs is GitHub-verified and matches the repo owner

03 · What Dead Letter can do

Prose above is summarized from the project's README and registry record - no invented capabilities.

Latest releases

v0.4.5 · 2026-09-28

dead-letter 0.4.5. It first ships the bounded convert_mbox MCP tool, the /dead-letter:mbox plugin command, and MCP server identity metadata (icon and titles). The analyze command and typesafe extra are experimental.…

v0.4.0 · 2026-09-19

Added · Generated VS Code and Cursor MCP install links, client-specific VS Code, · Cursor, and Cline configurations, and a Cline marketplace submission · candidate derived from the canonical server.json launch…

v0.3.1 · 2026-09-19

0.3.1 · Same code as 0.3.0 with two release-pipeline fixes, so this is the first release that publishes the OCI image and registers the MCPB and OCI packages with the MCP Registry: · The container publish job now…

04 · Who maintains Dead Letter

dead-letter is maintained by bigcactuslabs. It's the only MCP server we track from this author; the repo dates to Mar 2026.

05 · Facts

repository: github.com/bigcactuslabs/dead-letter
category: email - ranked #19 of 98 actively-maintained email servers as of 2026-09-30.
release cadence: 6 releases in the last 90 days (latest 2026-09-28)
registry: io.github.BigCactusLabs/dead-letter (active, first published 2026-07-06 · 5 versions)
packages: pypi:dead-letter · mcpb:https://github.com/BigCactusLabs/dead-letter/releases/download/v0.4.5/dead-letter-mcp-0.4.5.mcpb · oci:ghcr.io/bigcactuslabs/dead-letter@sha256:18ff617fb594196e12e3574809caf8ff5b79bea8a831f801b8fc2ac6418a82a1

06 · Dead Letter FAQ

What is Dead Letter?

Is Dead Letter still maintained?

Yes - as of 2026-09-30, its last commit was 2026-09-29 and it shipped 6 releases in the last 90 days. We re-verify nightly.

How do I install Dead Letter?

Run `uvx dead-letter`. The README does not document required environment variables for a basic install. You can also paste the ready-made client config above.

Does Dead Letter run locally?

Yes - it's a stdio server: it runs on your machine (via uvx) with your user's permissions. Your data stays local unless the server itself calls external APIs.

07 · Alternatives to Dead Letter

Alternatives to Dead Letter

Maintained email servers if Dead Letter isn't the fit.

More email MCP servers · Empty Inbox · Email (IMAP/SMTP) (boutquin) · Company Enrichment API · Fluxmail · Email MCP (codefuturist)

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