email-mcp

MCP server for email + calendar via classic Outlook on Windows (COM automation). No Azure app registration, no OAuth — it just drives the Outlook desktop client you're already signed into.

Requirements

• Windows 10/11

• Classic Outlook desktop (configured with at least one account)

• Node.js 14+

• PowerShell (built-in)

The "new" Outlook for Windows does not expose COM. If you're on the new Outlook and can't switch back, this won't work for you.

Related MCP server: outlook-mcp-server

Install / Run

Via npx straight from GitHub (no clone):

npx -y github:kerodkibatu/email-mcp

Or clone and run locally:

git clone https://github.com/kerodkibatu/email-mcp
cd email-mcp
npm install
node index.js

Claude Code / Claude Desktop config

Add to your .mcp.json (or claude_desktop_config.json):

{
  "mcpServers": {
    "email": {
      "command": "npx",
      "args": ["-y", "github:kerodkibatu/email-mcp"]
    }
  }
}

First launch will be slow (~10s) while npx clones + installs. Subsequent launches hit the cache.

Tools

Choosing the Sending Account

send_email, reply_email, and forward_email require an account parameter — a substring of the configured Outlook account name (typically the SMTP address). This is intentional: with multiple accounts configured (e.g. personal + work), defaulting to Outlook's primary account is a footgun — it's how personal mail leaks out of a work account or vice versa. Forcing the caller to name the account makes the send explicit.

If the supplied account doesn't match any configured account (case-insensitive substring), the tool errors and lists the available accounts. Run list_accounts first if you don't already know the name.

{
  "to": "client@example.com",
  "subject": "Status update",
  "body": "Heads up — ...",
  "account": "kerod@towlydigital.com"
}

Send As (Exchange "Send As" permission required)

send_email, reply_email, and forward_email accept an optional send_as parameter — an SMTP address to send AS. The recipient sees that address as the From, with no "on behalf of" disclosure. This is the true Exchange Send As, distinct from Send on Behalf.

Mechanically, the MCP sets SendUsingAccount to the account you provide (the transport mailbox) and then overwrites both the PR_SENT_REPRESENTING_* and PR_SENDER_* MAPI properties to point at send_as. Exchange validates the permission at submit time.

Requirements:

• The account user must have Send As permission on the send_as mailbox, granted server-side by an Exchange admin. The MCP cannot grant or check this — it can only attempt the send.

• The send_as address must be resolvable by Exchange — typically a mailbox in the same tenant. External addresses (gmail.com, etc.) will fail at resolution with an error.

• If the permission is missing, behavior depends on tenant policy: Exchange may bounce the message, silently downgrade it to "on behalf of", or leave it in the Outbox.

• This feature only works inside an Exchange organization that has explicitly authorized it. It cannot be used to spoof external senders.

{
  "to": "client@example.com",
  "subject": "Status update",
  "body": "Heads up — ...",
  "account": "admin@custom.com",
  "send_as": "contact@custom.com"
}

The response includes a sent_as field echoing the address when send_as was used.

Sending Attachments

send_email accepts an optional attachments array of absolute file paths. Each path must exist and point to a regular file; if any path is invalid, the tool returns an error and does not send. Forward and back slashes are both accepted on Windows; ~ and environment variables are not expanded — pass fully resolved paths.

{
  "to": "kerod@example.com",
  "subject": "Signed contract",
  "body": "See attached.",
  "account": "kerod@towlydigital.com",
  "attachments": [
    "C:\\Users\\Kerod\\Desktop\\contract.pdf",
    "C:/Users/Kerod/Desktop/cover-letter.pdf"
  ]
}

Downloading Attachments

The download_attachments tool extracts files from an email and saves them locally, returning the absolute folder path.

• Location: Files are saved under the user's Downloads folder: ~/Downloads/email-attachments/YYYY-MM-DD_sender-slug_subject-slug/.

• Inline Images: Logos and signature images are filtered out by default to avoid clutter. Set include_inline: true if you specifically need them.

• Idempotency: Re-running the tool on the same email safely skips re-downloading if the files already exist.

How it works

Each tool call writes a short PowerShell script to a temp file and executes it. The script attaches to a running Outlook instance via Marshal.GetActiveObject('Outlook.Application'), or launches one if none is running, then drives the MAPI namespace to read/write mail.

This means:

• Outlook must be installed (doesn't need to be open, but first call will launch it)

• Whatever account is signed into Outlook is what the MCP sees — no separate auth

• Sent mail appears in the user's Sent folder exactly as if they sent it manually

License

MIT — see LICENSE.