SkillFoxx

thunderbird-cli MCP

thunderbird-cli gives an agent Thunderbird mail through a tb CLI and 12 MCP tools, passwords stay in Thunderbird

  • 71 ★ on the repository
  • Last commit
  • MIT
MCP server

Broad access

Why this level

  • The agent reads all mail and attachments across accounts and can move and delete messages in bulk
  • Message content enters the model context, and links and attachments in mail can come from third parties
All reasons and checks

vitalio-sh/thunderbird-cliAuthor:vitalio-sh

Install

In your terminal, with SkillFoxx CLI

npx skillfoxx add mcp/thunderbird-cli

Detects the agents on your machine, shows the access level and pins the version.

Other ways to install

Access and checks

How we review

Broad accessThe tool can change data, run commands or handle secrets.

  • The agent reads all mail and attachments across accounts and can move and delete messages in bulk
  • Message content enters the model context, and links and attachments in mail can come from third parties

This is third-party code. Review the repository files before installing.

What it does

thunderbird-cli treats Mozilla Thunderbird as the source of truth for mail and exposes its capabilities as CLI commands and MCP tools. An agent reads, searches and writes email without touching passwords, OAuth flows or sync state: all IMAP and SMTP stay in Thunderbird. The project was tested on 22 accounts and more than 249,000 messages. It has four parts. A signed Thunderbird extension (128 or newer) calls the `messenger.*` APIs and holds 43 handlers. A `tb-bridge` daemon proxies HTTP to WebSocket with no business logic. The `tb` CLI has 38 commands, and the `tb-mcp` server gives 12 curated tools for Claude Desktop. Examples: `tb stats`, `tb search "invoice" --from aws --since 30d`, `tb read 89900 --max-body 500`, `tb bulk move`. Safe defaults: reply, forward and compose save as drafts, and permanent delete needs the `--confirm` flag. For token savings there is `--fields` selection, a compact mode and `--max-body` truncation. A companion skill teaches Claude to pick safe options and check trust metadata before following links.

Who it is for. People who keep mail in Thunderbird across several accounts and want Claude to sort it without handing over passwords.

Good fit when

  • You need to know how many unread messages sit across all accounts with a single `tb stats`
  • AWS invoices from the last 30 days have to be found by sender and date and their PDF attachments downloaded
  • Newsletters older than 30 days should move to the archive in bulk through `tb bulk move`
  • A reply to a colleague should be prepared but not sent: `tb reply` saves a draft
  • Claude Desktop should work with mail over MCP without IMAP libraries and OAuth

Not a fit when

  • You need mail without Thunderbird: the tool relies on its extension and bridge
  • You run Thunderbird older than 128: the extension is signed for 128 and newer
  • The agent should send mail by itself with no review: everything goes to drafts by default
  • You need a cloud service: the bridge and extension run only on your machine

Example request

Find AWS invoices from last month across all Thunderbird accounts, download the PDF attachments and save the reply to my colleague as a draft

MCP

Transport
stdio
Authentication
not required

Limitations

  • Thunderbird 128 or newer, the signed extension from the releases and a running `tb-bridge` daemon that stays up are required.
  • The CLI and bridge are Node.js, installed with `npm install -g thunderbird-cli thunderbird-cli-bridge`.
  • Mail is not cached: each command goes to Thunderbird directly, so it fails when Thunderbird is not running.
  • Message content reaches the agent, including third-party links and attachments: the project describes prompt-injection defenses in SECURITY.md, but double-check actions that depend on sender trust.

How to disable. Remove the extension in Thunderbird under Add-ons, stop the bridge in the terminal and uninstall the packages with `npm uninstall -g thunderbird-cli thunderbird-cli-bridge`. Delete the thunderbird block from `claude_desktop_config.json`.

FAQ

How do I connect thunderbird-cli to Claude Desktop?

Add a thunderbird server to `claude_desktop_config.json` with the command `npx` and args `-y thunderbird-cli-mcp`, then restart the app. The `tb-bridge` and the Thunderbird extension must be running.

Does the agent see my passwords?

No. All IMAP and SMTP stay in Thunderbird, and the CLI and MCP go through the extension and a local bridge.

Will the agent send mail without me knowing?

Not by default: reply, forward and compose save drafts, and permanent delete needs the `--confirm` flag.

How many commands and tools are there?

The `tb` CLI has 38 commands and the `tb-mcp` server gives 12 tools. The full list is in `docs/COMMANDS.md`.

Why is there a skill beside the MCP server?

The MCP server works without it, but the skill teaches Claude to choose safe options, save tokens with `--fields` and check trust metadata before following links. For Claude Code it is copied to `~/.claude/skills/`.

Discussion

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README in short

The README says IMAP libraries force an agent to handle credentials while Thunderbird already solves that, and lists features. Install, command examples, Claude Desktop setup, the skill, a four-component diagram and a comparison with notmuch, mu, himalaya and mutt follow.

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