Is Mailsandbox safe to use?

Mailsandbox has no known CVEs as of the latest MCPpedia security scan. It does not require authentication, so any local process can connect — keep this in mind in shared environments. Licensed under MIT.

How do I install Mailsandbox?

Mailsandbox can be installed by cloning its GitHub repository and following the setup instructions in the README.

What can Mailsandbox do?

Mailsandbox provides 4 tools: list_messages, get_message, search_messages, analyze_message. See the full tools list on the server page for descriptions and parameters.

What AI clients work with Mailsandbox?

Mailsandbox is compatible with Claude Desktop, Cursor, Claude Code, and most MCP clients that support stdio transport. It uses stdio transport.

Is Mailsandbox actively maintained?

Mailsandbox is less actively maintained — last commit was 212 days ago. It has 8 GitHub stars.

Mailsandbox

MailSandbox is a fast, zero-dependency email testing tool & API with a web UI, SMTP server, Postmark API emulation, and MCP server for AI-assisted debugging.

StaleNot tested

Communication Developer Tools

★ 8GitHub

60BNo CVEsstale4 toolsMIT

Quick Install

{
  "mcpServers": {
    "mailsandbox": {
      "command": "<see-readme>",
      "args": []
    }
  }
}

Setup guide

No install config available. Check the server's README for setup instructions.

Are you the author?

Add this badge to your README to show your security score and help users find safe servers.

Embed in your READMEAbout badges →

[![MCPpedia Score](https://mcppedia.org/api/badge/mailsandbox)](https://mcppedia.org/s/mailsandbox)

Should you use this server?

> Fork of Mailpit adding Postmark API emulation and an MCP server for AI-assisted debugging. > Inspired by and grateful to the original work on Mailpit and MailHog. See Credits.

✓

Is it safe?

No package registry to scan.

No authentication — any process on your machine can connect.

MIT. View license →

Is it maintained?

Last commit 212 days ago. 8 stars.

Will it work with my client?

Transport: stdio. Works with Claude Desktop, Cursor, Claude Code, and most MCP clients.

Context cost

4 tools. ~100 tokens (0.1% of 200K).

README

MailSandbox — email testing & simulation for developers

Fork of Mailpit adding Postmark API emulation and an MCP server for AI-assisted debugging.
Inspired by and grateful to the original work on Mailpit and MailHog. See Credits.

Repository • Installation • Usage • Postmark API • MCP Server

MailSandbox is a small, fast, low-memory, zero-dependency, multi-platform email testing tool & API for developers.
It provides an SMTP server, modern web interface, REST API, Postmark API emulation, and an MCP server for AI-powered workflows.

Features

🚀 Lightweight — single static binary or multi-arch Docker image
🌐 Modern Web UI — view HTML, source, headers, attachments, search & filter
📬 SMTP & POP3 servers — STARTTLS/SSL/TLS, authentication, forwarding, relaying
🔍 Testing tools — HTML check, link check, spam score, screenshots, mobile preview
🏷 Tagging & filtering — manual or automated (incl. plus addressing)
⚡ Performance — 100–200 emails/sec, automatic pruning (default 500 emails)
🧪 Chaos mode — inject SMTP errors to test resilience
🔔 Integrations — webhooks, browser notifications, List-Unsubscribe validation
🆕 Postmark API emulation — drop-in replacement for Postmark during development
🤖 MCP server — AI assistants (e.g., Claude Code) can list, search, and analyze messages

Installation

The web UI runs on http://0.0.0.0:8025 and SMTP on 0.0.0.0:1025.

Script (Linux & macOS)

sudo sh < <(curl -sL https://raw.githubusercontent.com/btafoya/mailsandbox/main/install.sh)

Static binary

Download from releases, rename to mailsandbox, and add to $PATH.

Docker

docker run -d --name mailsandbox   -p 8025:8025 -p 1025:1025   btafoya/mailsandbox

Usage

List options:

mailsandbox -h

Postmark API Emulation

Enable Postmark API emulation:

mailsandbox --postmark-api --postmark-token "your-secret-token"

Environment variables:

export MP_POSTMARK_API=true
export MP_POSTMARK_TOKEN=your-secret-token
mailsandbox

Example: Node.js

const postmark = require("postmark");
const client = new postmark.ServerClient("your-secret-token");
client.apiUrl = "http://localhost:8025";
client.sendEmail({ From:"a@x.com", To:"b@y.com", Subject:"Test", TextBody:"Hello" });

Endpoints:

POST /email

... View full README on GitHub

Test This Server

No automated test available for this server. Check the GitHub README for setup instructions.

Tools (4)

list_messages

list/filter emails

get_message

retrieve full message

search_messages

advanced search

analyze_message

HTML, links, spam scoring

Score Breakdown

MCPpedia Score

Click each category to see evidence

60B

Last scored 8h ago

How we score →

Security

16/30

No known vulnerabilities.

○

Known CVEs — No package registry to scan

✓

Tool safety — No dangerous patterns detected

✓

Tool poisoning — No poisoning indicators detected

✓

Injection vectors — No injection vectors detected

✗

Tool stability — Tool definitions changed since last scan

○

Dependency health — No package to analyze

✓

License — License: MIT

○

Authentication — No authentication required

○

Repository — active repo

CVEs checked daily via OSV.dev. Score algorithm is open source.

Reviews

Have you used this server?

Share your experience — it helps other developers decide.

How easy was setup?Did it work reliably?How was the documentation?

Frequently Asked Questions

Is Mailsandbox safe to use?: Mailsandbox has no known CVEs as of the latest MCPpedia security scan. It does not require authentication, so any local process can connect — keep this in mind in shared environments. Licensed under MIT.
How do I install Mailsandbox?: Mailsandbox can be installed by cloning its GitHub repository and following the setup instructions in the README.
What can Mailsandbox do?: Mailsandbox provides 4 tools: list_messages, get_message, search_messages, analyze_message. See the full tools list on the server page for descriptions and parameters.
What AI clients work with Mailsandbox?: Mailsandbox is compatible with Claude Desktop, Cursor, Claude Code, and most MCP clients that support stdio transport. It uses stdio transport.
Is Mailsandbox actively maintained?: Mailsandbox is less actively maintained — last commit was 212 days ago. It has 8 GitHub stars.

Similar servers

View all →

XcodeBuildMCP

Official

No CVEs97A

A Model Context Protocol (MCP) server and CLI that provides tools for agent use when working on iOS and macOS projects.

2 toolsremote5.2k46.6k/wk1d ago

Mcp_agent_mail

No CVEs95A

Asynchronous coordination layer for AI coding agents: identities, inboxes, searchable threads, and advisory file leases over FastMCP + Git + SQLite

6 toolsremote1.9k6783.6k/wk23h ago

Gemini Cli

No CVEs95A

An open-source AI agent that brings the power of Gemini directly into your terminal.

8 toolsremote101.3k814.6k/wk12h ago

XcodeBuildMCP

No CVEs95A

XcodeBuildMCP provides tools for Xcode project management, simulator management, and app utilities.

1 toolsremote5.2k20.6k/wk15d ago

MCP Security Weekly

Get CVE alerts and security updates for Mailsandbox and similar servers.

Discussion

Start a conversation

Ask a question, share a tip, or report an issue.

Has anyone used this with Cursor?How do you handle auth?Any alternatives?

MailSandbox — email testing & simulation for developers

Fork of Mailpit adding Postmark API emulation and an MCP server for AI-assisted debugging.
Inspired by and grateful to the original work on Mailpit and MailHog. See Credits.

Repository • Installation • Usage • Postmark API • MCP Server

Features

🚀 Lightweight — single static binary or multi-arch Docker image
🌐 Modern Web UI — view HTML, source, headers, attachments, search & filter
📬 SMTP & POP3 servers — STARTTLS/SSL/TLS, authentication, forwarding, relaying
🔍 Testing tools — HTML check, link check, spam score, screenshots, mobile preview
🏷 Tagging & filtering — manual or automated (incl. plus addressing)
⚡ Performance — 100–200 emails/sec, automatic pruning (default 500 emails)
🧪 Chaos mode — inject SMTP errors to test resilience
🔔 Integrations — webhooks, browser notifications, List-Unsubscribe validation
🆕 Postmark API emulation — drop-in replacement for Postmark during development
🤖 MCP server — AI assistants (e.g., Claude Code) can list, search, and analyze messages

Installation

The web UI runs on http://0.0.0.0:8025 and SMTP on 0.0.0.0:1025.

Script (Linux & macOS)

sudo sh < <(curl -sL https://raw.githubusercontent.com/btafoya/mailsandbox/main/install.sh)

Static binary

Download from releases, rename to mailsandbox, and add to $PATH.

Docker

docker run -d --name mailsandbox   -p 8025:8025 -p 1025:1025   btafoya/mailsandbox

Usage

List options:

mailsandbox -h

Postmark API Emulation

Enable Postmark API emulation:

mailsandbox --postmark-api --postmark-token "your-secret-token"

Environment variables:

export MP_POSTMARK_API=true
export MP_POSTMARK_TOKEN=your-secret-token
mailsandbox

Example: Node.js

const postmark = require("postmark");
const client = new postmark.ServerClient("your-secret-token");
client.apiUrl = "http://localhost:8025";
client.sendEmail({ From:"a@x.com", To:"b@y.com", Subject:"Test", TextBody:"Hello" });

Endpoints:

POST /email

... View full README on GitHub