Outbox

Name: Outbox
Author: fieldcure

by fieldcureversion 2.1.3i★ –iRuns on your computer

Registry nameio.github.fieldcure/outbox

Install

Overview

Description from the maker (original English)

Multi-channel messaging MCP server for Slack, Telegram, Email, KakaoTalk, and Discord.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi1 of 1 passedChecked from public information; code not scanned yet
UsageiNot measured yet★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs on your computer
Transport: stdio
Category: Chat & email

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 1 of 1 passed
Runs on your computer with your user’s permissions (files, network, apps).
The registry lists no key to fill in.

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json

{
  "mcpServers": {
    "outbox": {
      "command": "dnx",
      "args": [
        "FieldCure.Mcp.Outbox",
        "--yes"
      ]
    }
  }
}

Run this in your terminal

claude mcp add outbox -- dnx FieldCure.Mcp.Outbox --yes

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "outbox": {
      "command": "dnx",
      "args": [
        "FieldCure.Mcp.Outbox",
        "--yes"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "outbox": {
      "type": "stdio",
      "command": "dnx",
      "args": [
        "FieldCure.Mcp.Outbox",
        "--yes"
      ]
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account fieldcure, which owns the repo
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
– Not applicable
Endpoint responds
This one runs on your computer; there is no internet endpoint
– Not applicable
Sign-in with OAuth
Runs on your computer and uses local settings instead
… Not checked yet
No hidden instructions in tool descriptions
Runs on your computer; we can only read tool lists from internet endpoints

Compared with others in Chat & emaili

More stars than 0% of the other 1771 servers in this category
Published to the registry more recently than 10% of the other 1771 servers in this category
Basic checks equal to or better than 100% of the other 1771 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Outbox safe?

It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed –, and the latest version (2.1.3) reached the registry 5 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need .NET on your computer.

What can I use instead?

In the same category: Vexa, emailmd, MCP WhatsApp Cloud

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

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by Vexa-ai

Meeting bot and transcripts for Google Meet, Teams and Zoom. Live or after, speakers labelled.

Runs in the cloud★ 2,949Apache-2.0Updated 2 months ago

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emailmd

by anypost

Render markdown into email-safe HTML, lint drafts for deliverability problems, and preview emails.

Computer or cloud★ 1,385MITUpdated 31 days ago

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MCP WhatsApp Cloud

by codespar

MCP server for WhatsApp Cloud API (Meta) — messages, media, and templates via Graph API

Runs on your computer★ 277MITUpdated 5 months ago

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

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

Tool	Description	Confirmation
`list_channels`	List all configured messaging channels	—
`add_channel`	Add a new channel (MCP elicitation for all channel types; Microsoft/KakaoTalk require a local browser on the MCP host)	—
`send_message`	Send a message through a configured channel	Required
`remove_channel`	Remove a channel and its stored credentials	Required

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, Discord webhook URLs, SMTP passwords, etc.) resolve at send time in this order: in-memory cache → env var OUTBOX_{CHANNEL_ID}_{FIELD} → plaintext in channels.json → MCP elicitation. The CLI add_channel flow writes directly into channels.json for a zero-configuration local experience. This is an intentional local-trust choice with the same same-user boundary as tokens.json, documented in ADR-001 Principle 2. For shared hosts, CI, or headless deployments, set the env vars explicitly and leave channels.json secret fields empty.

Channel	Protocol	Setup
Slack	Web API (`chat.postMessage`)	Guide
Telegram	Client API (WTelegramClient)	Guide
Gmail	SMTP	Guide
Naver	SMTP	Guide
Microsoft	Graph API (`/me/sendMail`)	Guide
KakaoTalk	Kakao REST API	Guide
Discord	Webhook API	Guide
Custom SMTP	User-defined	Guide

Static Secret Environment Variables

When a channel requires a static secret at send time, Outbox looks for an environment variable named:

OUTBOX_<CHANNEL_ID>_<FIELD>

Examples:

OUTBOX_MICROSOFT_1_CLIENT_SECRET
OUTBOX_KAKAOTALK_1_API_KEY
OUTBOX_KAKAOTALK_1_CLIENT_SECRET
OUTBOX_SMTP_GMAIL_1_PASSWORD

If the variable is unset and the MCP client supports elicitation, Outbox prompts for it interactively and caches it for the current session.

CLI Commands

fieldcure-mcp-outbox                      # Start MCP server (stdio)

fieldcure-mcp-outbox add slack # Add Slack channel fieldcure-mcp-outbox add telegram # Add Telegram channel fieldcure-mcp-outbox add gmail # Add Gmail SMTP channel fieldcure-mcp-outbox add naver # Add Naver SMTP channel fieldcure-mcp-outbox add smtp # Add custom SMTP channel fieldcure-mcp-outbox add microsoft # Add Microsoft (Outlook/M365) channel fieldcure-mcp-outbox add kakaotalk # Add KakaoTalk channel fieldcure-mcp-outbox add discord # Add Discord channel fieldcure-mcp-outbox list # List configured channels fieldcure-mcp-outbox remove # Remove a channel

Data Storage

Data	Location
Channel metadata	`%LOCALAPPDATA%\FieldCure\Mcp.Outbox\channels.json`
OAuth tokens	`%LOCALAPPDATA%\FieldCure\Mcp.Outbox\tokens.json`
Telegram sessions	`%LOCALAPPDATA%\FieldCure\Mcp.Outbox\sessions\`

tokens.json is stored in plain JSON and protected by filesystem permissions:

Windows: ACL restricted to the current user
Linux/macOS: mode 0600

This protects against other local users on the same machine, but not against compromise of the same OS user account.

Project Structure

src/FieldCure.Mcp.Outbox/

├── Program.cs # Entry point: MCP server vs CLI branching ├── Channels/ │ ├── IChannel.cs # Channel interface + SendRequest/SendResult │ ├── ChannelFactory.cs # Channel instantiation by type │ ├── SlackChannel.cs # Slack Web API │ ├── TelegramChannel.cs # WTelegramClient │ ├── SmtpChannel.cs # MailKit SMTP │ ├── MicrosoftChannel.cs # Microsoft Graph API │ ├── KakaoTalkChannel.cs # Kakao REST API │ └── DiscordChannel.cs # Discord Webhook API ├── Tools/ │ ├── ListChannelsTool.cs # list_channels │ ├── AddChannelTool.cs # add_channel (elicitation + browser OAuth for Kakao/Microsoft) │ ├── RemoveChannelTool.cs # remove_channel │ └── SendMessageTool.cs # send_message ├── Interaction/ │ ├── IElicitGate.cs # Minimal MCP elicitation surface for tests │ └── McpServerElicitGate.cs # Production adapter around McpServer ├── OAuth/ │ └── BrowserOAuthFlow.cs # Localhost callback + Process.Start + elicit race (MCP and CLI entry points) ├── Credentials/ │ └── OutboxSecretResolver.cs # cache → env → channels.json → elicitation ├── Setup/ │ ├── SetupRunner.cs # CLI router (diagnostic path) │ ├── ConsoleHelper.cs # Masked input, prompts │ ├── SlackSetup.cs │ ├── TelegramSetup.cs │ ├── SmtpSetup.cs │ ├── MicrosoftSetup.cs │ ├── KakaoTalkSetup.cs │ └── DiscordSetup.cs └── Configuration/ ├── ChannelStore.cs # channels.json persistence (metadata + static-secret fallback) ├── OAuthTokenStore.cs # tokens.json persistence (OAuth access/refresh, user-only file perms) └── SmtpPresets.cs # SMTP preset definitions

Development

# Build

dotnet build

Test

dotnet test

Pack as dotnet tool

dotnet pack src/FieldCure.Mcp.Outbox -c Release

License

MIT

Outbox

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Chat & emaili

Common questions

Alternatives

Vexa

emailmd

MCP WhatsApp Cloud

README from the maker

FieldCure MCP Outbox Server

Features

Why Outbox?

Installation

dotnet tool (recommended)

From source

Requirements

Configuration

Claude Desktop

VS Code (Copilot)

From source (without dotnet tool)

Tools

Channels

Static Secret Environment Variables

CLI Commands

Data Storage

Project Structure

Development

Test

Pack as dotnet tool

See Also

License