tbird-mcp — Thunderbird-aware Mail MCP

An MCP server that reads/searches your mail from Thunderbird's local store and sends mail over SMTP from any of your identities, then files a copy in the account's Sent folder so it shows up in Thunderbird normally.

Thunderbird has no programmatic send API, so "send through Thunderbird" really means: read Thunderbird's on-disk mbox files, but put outgoing mail on the wire ourselves via SMTP. Account and identity configuration is auto-discovered from Thunderbird's prefs.js — you don't re-enter any of it.

What v1 does

• Read — every account, from the local mbox store. Streams even multi-gigabyte folders without loading them into memory, and skips messages Thunderbird has flagged deleted-but-not-compacted.

• Send — any plain-SMTP identity (Migadu, Zoho, Fastmail, generic SMTP, …), auto-discovered from Thunderbird.

• Deferred to v2 — sending as Outlook/hotmail. Microsoft disabled basic SMTP auth for personal accounts, so it needs a Microsoft Graph / OAuth2 app registration. The transport seam is in place (transports.GraphTransport); until then, send_mail from an Outlook identity returns a clear error.

Related MCP server: Email MCP Server

Tools

search_mail returns an opaque id per message; pass it to the read/extract tools. send_mail defaults to dry_run=True and returns a preview — pass dry_run=False to actually send.

Install

cd ~/agents/personal/mcp-servers/tbird-mcp
uv sync                 # creates .venv with the mcp SDK
uv run python tests/make_fixture.py   # (tests only) generate the sample mbox
uv run pytest -q        # 20+ tests, no real mail sent

1. Register with Claude Code

Add to your MCP config (e.g. ~/.claude.json, or via claude mcp add):

{
  "mcpServers": {
    "tbird": {
      "command": "uv",
      "args": ["run", "--directory",
               "/path/to/tbird-mcp",
               "tbird-mcp"]
    }
  }
}

Optional environment overrides:

• TBIRD_PROFILE — absolute path to a specific Thunderbird profile dir (default: the active profile from profiles.ini).

• TBIRD_CREDENTIALS — path to the credentials file (default: ~/.config/tbird-mcp/credentials.toml).

2. Add credentials (only needed for sending)

Reading needs no credentials. Sending does:

mkdir -p ~/.config/tbird-mcp
cp credentials.toml.example ~/.config/tbird-mcp/credentials.toml
chmod 600 ~/.config/tbird-mcp/credentials.toml
$EDITOR ~/.config/tbird-mcp/credentials.toml

Use app passwords, not your account login passwords:

• Migadu — Admin → Mailboxes → the mailbox → App passwords → create one. Aliases can't authenticate; create the app password on the real mailbox and point each alias at it with an [identity."alias@…"] auth_user = "…" block. One mailbox app password typically covers all aliases on its domain.

• Zoho — myaccount.zoho.com → Security → App Passwords → generate.

After editing, call reload_config (or restart the server).

3. (Later) v2 — sending as Outlook/hotmail

Outlook/hotmail send needs a one-time, free Azure app registration to obtain a client ID, then OAuth2 device-code auth against Microsoft Graph's Mail.Send scope. The graph transport slot is already wired into the identity registry; v2 fills in GraphTransport.send. Until then, send from a Migadu/Zoho/SMTP identity, or use Thunderbird directly.

Notes / limitations

• Search streams the whole folder file, so a query against a multi-gigabyte folder takes a few seconds — narrow with account + a tight limit.

• Message ids encode a byte offset into the mbox; if Thunderbird compacts a folder, re-run the search to get fresh ids.

• Sub-folders inside *.sbd directories aren't enumerated in v1 (top-level folders only).