FieldCure MCP Outbox Server

A multi-channel messaging Model Context Protocol (MCP) server that sends messages through Slack, Telegram, Email (Gmail, Naver, Microsoft Graph API), KakaoTalk, and Discord. Built with C# and the official MCP C# SDK.

Features

• Multiple messaging channels — Slack, Telegram, Email (Gmail, Naver, Microsoft Graph API), KakaoTalk, Discord
• 4 MCP tools — list_channels, add_channel, send_message, remove_channel
• Cross-platform credential flow — runtime secrets can come from env vars or MCP elicitation; OAuth tokens are stored separately for refresh lifecycle
• CLI channel setup — interactive console for browser/OAuth flows where applicable
• SMTP presets — Gmail, Naver with one-command setup
• Microsoft Graph API — OAuth 2.0 browser flow for Outlook / M365 email with automatic token refresh
• KakaoTalk OAuth — localhost callback flow with automatic token refresh
• Telegram Client API — send to Saved Messages via WTelegramClient
• Stdio transport — standard MCP subprocess model via JSON-RPC over stdin/stdout

Why Outbox?

Existing MCP servers are channel-specific — one for Slack, another for Gmail, yet another for Telegram. Each requires separate installation, configuration, and the LLM must know which tool to call for each channel.

Outbox takes a different approach:

• One tool, multiple channels — send_message abstracts away channel differences. The LLM doesn't need to know Slack API vs SMTP vs Kakao REST.
• Credential isolation — OAuth refresh tokens live in tokens.json with current-user-only file permissions; MCP tool flows can resolve secrets at runtime via env vars or elicitation.
• Single install — dotnet tool install -g gives you 4 channels. No need to install and configure separate servers per channel.
• KakaoTalk support — Currently the only MCP server with KakaoTalk messaging, essential for Korean users.

Installation

dotnet tool (recommended)

dotnet tool install -g FieldCure.Mcp.Outbox

After installation, the fieldcure-mcp-outbox command is available globally.

From source

git clone https://github.com/fieldcure/fieldcure-mcp-outbox.git
cd fieldcure-mcp-outbox
dotnet build

Requirements

• .NET 8.0 Runtime or later
• Cross-platform (Windows, Linux, macOS)

Configuration

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "outbox": {
      "command": "fieldcure-mcp-outbox"
    }
  }
}

VS Code (Copilot)

Add to .vscode/mcp.json:

{
  "servers": {
    "outbox": {
      "command": "fieldcure-mcp-outbox"
    }
  }
}

From source (without dotnet tool)

{
  "mcpServers": {
    "outbox": {
      "command": "dotnet",
      "args": [
        "run",
        "--project", "C:\\path\\to\\fieldcure-mcp-outbox\\src\\FieldCure.Mcp.Outbox"
      ]
    }
  }
}

Tools

Channels

OAuth tokens for Microsoft/KakaoTalk are stored in tokens.json so the server can refresh them across runs (current-user-only file permissions — Windows ACL / Unix 0600).

Static secrets (Slack bot tokens, Disc

... View full README on GitHub