MCP Mail Server

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A Model Context Protocol server for IMAP/SMTP email operations with Claude, Cursor, and other AI assistants.

Features

• IMAP Operations: Search, read, and manage emails across mailboxes

• SMTP Support: Send emails with HTML/text content and attachments

• Attachment Management: View attachment metadata and save attachments to local files

• Secure Configuration: Environment-based setup with TLS/SSL support

• AI-Friendly: Natural language commands for email operations

• Auto Connection Management: Automatic IMAP/SMTP connection handling

• Multi-Mailbox Support: Access INBOX, Sent, and custom folders

Related MCP server: Mailbridge MCP

Changelog

[1.2.1] - 2026-03-18

Fixed

• Fixed search criteria (FROM/TO/SUBJECT/BODY/KEYWORD/SINCE) not using nested array format, causing errors on TO and other searches

• Fixed search() wrapping criteria in an extra array, breaking compound search conditions

• Fixed deleteMessage() failing silently when the mailbox was opened in read-only mode

• Fixed getRecentMessages() misusing the IMAP RECENT flag; now fetches latest N messages by UID

• Fixed getRecentMessages() / getUnseenMessages() relying on leftover mailbox state from previous operations

• Fixed cleanReplySubject() only stripping one Re: prefix layer, causing false negatives in unreplied detection

• Fixed email date stored as locale string causing inconsistent new Date() parsing across platforms; changed to ISO 8601

• Fixed ensureIMAPConnection() having no timeout while waiting for concurrent initialization

• Fixed saveSentMessage() always returning sentFolderSaved: true even when save failed

• Fixed handleGetMessages() / handleDeleteMessage() relying on currentBox state to locate messages

• Fixed reply_to_email writing literal "undefined" into the body when text is empty

Added

• All search tools now support an inboxOnly parameter to restrict search to INBOX only

Improved

• ensureSMTPConnection() now has concurrency guard with 30-second timeout, consistent with IMAP

• Sent mailbox auto-detected via RFC 6154 \Sent special-use attribute with result caching, compatible with all mail providers

• saveMessageToFolder() simplified; skips saving if no sent folder is found

• Search now uses slice(-limit) to fetch the newest messages first, preventing empty results after date filtering

• HTML-escape applied to quoted content in reply emails to prevent XSS injection

For the full version history, see CHANGELOG.md.

Quick Start

1. Install: npm install -g mcp-mail-server

2. Configure environment variables (see Configuration)

3. Add to your MCP client configuration

4. Use natural language: "Show me unread emails from today"

Installation

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "mcp-mail-server": {
      "command": "npx",
      "args": ["-y", "mcp-mail-server"],
      "env": {
        "IMAP_HOST": "your-imap-server.com",
        "IMAP_PORT": "993",
        "IMAP_SECURE": "true",
        "SMTP_HOST": "your-smtp-server.com",
        "SMTP_PORT": "465",
        "SMTP_SECURE": "true",
        "EMAIL_USER": "your-email@domain.com",
        "EMAIL_PASS": "your-password"
      }
    }
  }
}

Add to your Cursor MCP settings:

{
  "mcpServers": {
    "mcp-mail-server": {
      "command": "npx",
      "args": ["-y", "mcp-mail-server"],
      "env": {
        "IMAP_HOST": "your-imap-server.com",
        "IMAP_PORT": "993",
        "IMAP_SECURE": "true",
        "SMTP_HOST": "your-smtp-server.com",
        "SMTP_PORT": "465",
        "SMTP_SECURE": "true",
        "EMAIL_USER": "your-email@domain.com",
        "EMAIL_PASS": "your-password"
      }
    }
  }
}

Add using the claude mcp add command:

claude mcp add mcp-mail-server \
  -e IMAP_HOST=your-imap-server.com \
  -e IMAP_PORT=993 \
  -e IMAP_SECURE=true \
  -e SMTP_HOST=your-smtp-server.com \
  -e SMTP_PORT=465 \
  -e SMTP_SECURE=true \
  -e EMAIL_USER=your-email@domain.com \
  -e EMAIL_PASS=your-password \
  -- npx -y mcp-mail-server

Or manually add to .claude/settings.json:

{
  "mcpServers": {
    "mcp-mail-server": {
      "command": "npx",
      "args": ["-y", "mcp-mail-server"],
      "env": {
        "IMAP_HOST": "your-imap-server.com",
        "IMAP_PORT": "993",
        "IMAP_SECURE": "true",
        "SMTP_HOST": "your-smtp-server.com",
        "SMTP_PORT": "465",
        "SMTP_SECURE": "true",
        "EMAIL_USER": "your-email@domain.com",
        "EMAIL_PASS": "your-password"
      }
    }
  }
}

Add to codex.json in your project root:

{
  "mcpServers": {
    "mcp-mail-server": {
      "command": "npx",
      "args": ["-y", "mcp-mail-server"],
      "env": {
        "IMAP_HOST": "your-imap-server.com",
        "IMAP_PORT": "993",
        "IMAP_SECURE": "true",
        "SMTP_HOST": "your-smtp-server.com",
        "SMTP_PORT": "465",
        "SMTP_SECURE": "true",
        "EMAIL_USER": "your-email@domain.com",
        "EMAIL_PASS": "your-password"
      }
    }
  }
}

Other MCP clients can be configured similarly. The core configuration is:

{
  "mcpServers": {
    "mcp-mail-server": {
      "command": "npx",
      "args": ["-y", "mcp-mail-server"],
      "env": {
        "IMAP_HOST": "your-imap-server.com",
        "IMAP_PORT": "993",
        "IMAP_SECURE": "true",
        "SMTP_HOST": "your-smtp-server.com",
        "SMTP_PORT": "465",
        "SMTP_SECURE": "true",
        "EMAIL_USER": "your-email@domain.com",
        "EMAIL_PASS": "your-password"
      }
    }
  }
}

Refer to your specific client's documentation for the appropriate configuration file location.

Available Tools

Connection Management

• connect_all: No parameters required

• get_connection_status: No parameters required

• disconnect_all: No parameters required

Mailbox Operations

• open_mailbox: mailboxName (string, default: "INBOX"), readOnly (boolean)

• list_mailboxes: No parameters required

Search Operations

• search_by_sender: sender (string, email address), startDate (string, optional), endDate (string, optional)

• search_by_subject: subject (string, keywords), startDate (string, optional), endDate (string, optional)

• search_by_recipient: recipient (string, email address), startDate (string, optional), endDate (string, optional)

• search_by_body: text (string, search text), startDate (string, optional), endDate (string, optional)

• search_since_date: date (string, date format)

• search_unread_from_sender: sender (string, email address), startDate (string, optional), endDate (string, optional)

• search_unreplied_from_sender: sender (string, email address), startDate (string, optional), endDate (string, optional), limit (number, optional)

• search_with_keyword: keyword (string, keyword), startDate (string, optional), endDate (string, optional)

• search_all_messages: startDate (string, optional), endDate (string, optional), limit (number, optional, default: 50)

Message Operations

• get_message_count: No parameters required

• get_unseen_messages: No parameters required

• get_recent_messages: No parameters required

• get_message: uid (number), markSeen (boolean, optional)

• get_messages: uids (array), markSeen (boolean, optional)

• delete_message: uid (number)

Email Sending

• send_email: to (string), subject (string), text (string, optional), html (string, optional), cc (string, optional), bcc (string, optional), attachments (string[], optional, absolute file paths)

• reply_to_email: originalUid (number), text (string), html (string, optional), replyToAll (boolean, optional), includeOriginal (boolean, optional)

Attachment Operations

• get_attachments: uid (number) — Returns metadata: filename, contentType, size, index

• save_attachment: uid (number), savePath (string, absolute path), attachmentIndex (number, optional, 0-based), returnBase64 (boolean, optional, default: false)

Usage Examples

Use natural language commands with your AI assistant:

Basic Operations

• "Connect to my email servers"

• "Show me all unread emails"

• "Search for emails from boss@company.com"

• "Send an email to team@company.com about the meeting"

• "Reply to email with UID 123"

Advanced Searches

• "Find emails with 'urgent' in the subject from last week"

• "Show me unreplied emails from boss@company.com"

• "Search emails sent to team@company.com"

• "Get all emails from the Sales folder"

• "Show unread emails from boss@company.com"

• "Show me all emails from the last 7 days"

• "List all messages, limit to 20"

Email Management

• "Delete the email with UID 123"

• "Mark recent emails as read"

• "List all my email folders"

Attachment Operations

• "Show me the attachments of email UID 456"

• "Save all attachments from email UID 456 to D:/Downloads"

• "Download the first attachment from email UID 789"

• "Send an email to team@company.com with attachment D:/report.pdf"

Configuration

Environment Variables

⚠️ All variables are required

Optional variables

Transport Mode (stdio / HTTP)

By default the server runs over stdio (the standard MCP transport for local clients). It can also run as a Streamable HTTP server, optionally over HTTPS.

When a certificate and key are found, the server runs over HTTPS; otherwise it falls back to plaintext HTTP with a warning.

Generate a locally-trusted certificate with mkcert:

mkcert -install   # one-time: install the local CA
mkcert -cert-file certs/localhost-cert.pem -key-file certs/localhost-key.pem localhost 127.0.0.1 ::1

Run in HTTP mode:

MCP_TRANSPORT=http MCP_HTTP_PORT=8443 npm start
# → MCP endpoint:  https://localhost:8443/mcp
# → Health check:  https://localhost:8443/health

The MCP endpoint is served at /mcp and supports session management (via the mcp-session-id header) and SSE streaming, per the Streamable HTTP spec.

Common Email Providers

IMAP_HOST=imap.gmail.com
IMAP_PORT=993
IMAP_SECURE=true
SMTP_HOST=smtp.gmail.com
SMTP_PORT=465
SMTP_SECURE=true
EMAIL_USER=your-email@gmail.com
EMAIL_PASS=your-app-password

Note: Use App Passwords instead of your regular password.

IMAP_HOST=outlook.office365.com
IMAP_PORT=993
IMAP_SECURE=true
SMTP_HOST=smtp.office365.com
SMTP_PORT=587
SMTP_SECURE=true
EMAIL_USER=your-email@outlook.com
EMAIL_PASS=your-password

Security Notes

• Use App Passwords: Enable 2FA and use app-specific passwords when available

• TLS/SSL Required: Always use secure connections (IMAP_SECURE=true, SMTP_SECURE=true)

• Environment Variables: Never hardcode credentials in configuration files

Development

1. Clone the repository:

   git clone https://github.com/yunfeizhu/mcp-mail-server.git
   cd mcp-mail-server

2. Install dependencies:

   npm install

3. Build the project:

   npm run build

4. Set environment variables:

   export IMAP_HOST=your-imap-server.com
   export IMAP_PORT=993
   export IMAP_SECURE=true
   export SMTP_HOST=your-smtp-server.com
   export SMTP_PORT=465
   export SMTP_SECURE=true
   export EMAIL_USER=your-email@domain.com
   export EMAIL_PASS=your-password

5. Run the server:

   npm start

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License - see LICENSE file for details.

Package Information:

• Package: mcp-mail-server

• Node.js: ≥18.0.0

• Repository: GitHub

• Issues: Report bugs