JMAP MCP Server

A Model Context Protocol (MCP) server that provides tools for interacting with JMAP (JSON Meta Application Protocol) email servers. Built with Deno and using the @htunnicliff/jmap-jam client library.

Features

Email Management Tools

• Search Emails: Search emails with text queries, sender/recipient filters, date ranges, and keywords
• Get Emails: Retrieve specific emails by ID with full details
• Get Threads: Retrieve email threads (conversation chains)
• Mark Emails: Mark emails as read/unread, flagged/unflagged
• Move Emails: Move emails between mailboxes
• Delete Emails: Delete emails permanently

Mailbox Management

• Get Mailboxes: List all mailboxes/folders with hierarchy support

Email Composition

• Send Email: Compose and send new emails with support for plain text and HTML
• Reply to Email: Reply to existing emails with reply-all support

Key Capabilities

• Full JMAP RFC 8620/8621 compliance via jmap-jam
• Comprehensive input validation with Zod schemas
• Pagination support for all list operations
• Rich error handling and connection management
• Functional programming patterns throughout
• TypeScript support with strong typing

Installation

Prerequisites

• Deno v1.40 or later
• A JMAP-compliant email server (e.g., Cyrus IMAP, Stalwart Mail Server, FastMail)
• Valid JMAP authentication credentials

Setup

Add the following to your agent of choice:

{
  "mcpServers": {
    "fastmail": {
      "type": "stdio",
      "command": "deno",
      "args": [
        "run",
        "--allow-net=api.fastmail.com",
        "--allow-env=JMAP_SESSION_URL,JMAP_BEARER_TOKEN,JMAP_ACCOUNT_ID",
        "jsr:@wyattjoh/jmap-mcp@0.1.1"
      ],
      "env": {
        "JMAP_SESSION_URL": "https://api.fastmail.com/jmap/session",
        "JMAP_BEARER_TOKEN": "API_TOKEN"
      }
    }
  }
}

Usage

Environment Variables

Variable	Required	Description
JMAP_SESSION_URL	Yes	JMAP server session URL (usually ends with /.well-known/jmap)
JMAP_BEARER_TOKEN	Yes	Bearer token for authentication
JMAP_ACCOUNT_ID	No	Account ID (auto-detected if not provided)

Available Tools

search_emails

Search for emails with various filters.

Parameters:

• query (optional): Text search query
• from (optional): Filter by sender email address
• to (optional): Filter by recipient email address
• subject (optional): Filter by subject text
• inMailbox (optional): Search within specific mailbox
• hasKeyword (optional): Filter by keyword (e.g., '$seen', '$flagged')
• notKeyword (optional): Exclude by keyword
• before (optional): Only emails before date (ISO datetime)
• after (optional): Only emails after date (ISO datetime)
• limit (optional): Max results (1-100, default: 50)
• position (optional): Starting position for pagination (default: 0)

get_emails

Retrieve specific emails by their IDs.

Parameters:

• ids: Array of email IDs (1-50 IDs)
• properties (optional): Specific properties to return

get_mailboxes

Get list of mailboxes/folders.

Parameters:

• parentId (optional): Filter by parent mailbox
• limit (optional): Max results (1-200, default: 100)
• position (optional): Starting position for pagination

get_threads

Get email threads by their IDs.

Parameters:

• ids: Array of thread IDs (1-20 IDs)

mark_emails

Mark emails with keywords (read/unread, flagged/unflagged).

Parameters:

• ids: Array of email IDs (1-100 IDs)
• seen (optional): Mark as read (true) or unread (false)
• flagged (optional): Mark as flagged (true) or unflagged (false)

move_emails

Move emails to a different mailbox.

Parameters:

• ids: Array of email IDs (1-100 IDs)
• mailboxId: Target mailbox ID

delete_emails

Delete emails permanently.

Parameters:

• ids: Array of email IDs (1-100 IDs)

send_email

Send a new email.

Parameters:

• to: Array of recipients with name and email
• cc (optional): Array of CC recipients
• bcc (optional): Array of BCC recipients
• subject: Email subject
• textBody (optional): Plain text body
• htmlBody (optional): HTML body
• identityId (optional): Identity to send from

reply_to_email

Reply to an existing email.

Parameters:

• emailId: ID of email to reply to
• replyAll (optional): Reply to all recipients (default: false)
• subject (optional): Custom reply subject
• textBody (optional): Plain text body
• htmlBody (optional): HTML body
• identityId (optional): Identity to send from

JMAP Server Compatibility

This server should work with any JMAP-compliant email server, including:

• Cyrus IMAP 3.0+
• Stalwart Mail Server
• FastMail (commercial)
• Apache James (with JMAP support)

Development

Running in Development

deno run --allow-env --allow-net --watch src/mod.ts

Testing

# Test connection
deno run --allow-env --allow-net src/mod.ts

Architecture

The server is built using:

• Deno: Modern JavaScript/TypeScript runtime
• @modelcontextprotocol/sdk: MCP server framework
• jmap-jam: Lightweight, typed JMAP client
• Zod: Runtime type validation

Security

• All input is validated using Zod schemas
• Environment variables are used for sensitive configuration
• No secrets are logged or exposed in responses
• Follows JMAP security best practices

Contributing

1. Fork the repository
2. Create a feature branch
3. Make changes following the functional programming style
4. Test your changes thoroughly
5. Submit a pull request

License

MIT License - see LICENSE file for details.

Related Projects

• jmap-jam - JMAP client library
• Model Context Protocol - MCP specification
• JMAP RFC 8620 - JMAP core protocol
• JMAP RFC 8621 - JMAP for Mail