Fastmail MCP Server (Unofficial)

Unofficial Model Context Protocol server for Fastmail integration.

Setup Instructions

1. Get Your Fastmail API Token

1. Log in to Fastmail
2. Go to Settings → Privacy & Security → API tokens
3. Click New API token
4. Give it a name (e.g., "Claude MCP")
5. Select the required scopes: Mail (read/write as needed)
6. Copy the generated token

2. Configure Claude Code

Add the following to your Claude Code MCP settings (~/.claude/claude_desktop_config.json or project .mcp.json):

{
  "mcpServers": {
    "fastmail": {
      "type": "url",
      "url": "https://fastmail-mcp.vercel.app/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_FASTMAIL_API_TOKEN"
      }
    }
  }
}

Security Note: Keep your API token secure. Never commit it to version control. Consider using environment variables or a secrets manager.

Available Tools

mailbox_get

Get mailbox information (folders) - list all mailboxes or get specific ones by ID.

email_query

Query emails with filters and sorting.

• mailboxId (optional): Mailbox ID to search in
• limit (optional, default: 10): Maximum number of emails to return
• from (optional): Filter by sender
• to (optional): Filter by recipient
• subject (optional): Filter by subject text
• hasKeyword (optional): Filter by keyword (e.g., $seen, $flagged)
• notKeyword (optional): Filter by absence of keyword
• before (optional): Filter by date (ISO format)
• after (optional): Filter by date (ISO format)
• sort (optional, default: receivedAt): Sort by property
• ascending (optional, default: false): Sort order

email_get

Get specific emails by their IDs.

• emailIds (required): Array of email IDs to retrieve
• accountId (optional): Account ID (auto-detected if not provided)
• properties (optional): Specific properties to fetch
• fetchTextBodyValues (optional): Fetch text/plain body values
• fetchHTMLBodyValues (optional): Fetch text/html body values
• fetchAllBodyValues (optional): Fetch all text body values
• maxBodyValueBytes (optional): Maximum size in bytes for body values

email_send

Send emails with support for plain text, HTML, or both.

• to (required): Recipient email address
• subject (required): Email subject
• body (required): Plain text body
• htmlBody (optional): HTML body for multipart/alternative emails
• identityId (optional): Identity ID to send from

email_set

Update emails: move to a mailbox and/or set flags. Both operations can be combined in a single call.

• emailIds (required): Array of email IDs to update (1-50)
• mailboxId (optional): Target mailbox ID, or a well-known role: trash, archive, inbox, drafts, junk, sent
• flags (optional): Array of flags to set: read/unread, flagged/unflagged, answered/unanswered, draft/undraft
• accountId (optional): Account ID (auto-detected if not provided)

At least one of mailboxId or flags must be provided.

API Endpoints

• POST /mcp - MCP protocol endpoint
• GET /health - Health check endpoint

Development

pnpm install   # Install dependencies
pnpm dev       # Watch mode for TypeScript compilation
pnpm build     # Build for production
pnpm start     # Run local server
pnpm deploy    # Deploy to Vercel

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This is an unofficial community project and is not affiliated with Fastmail.

Source code and issues: GitHub