Mailsink

Name: Mailsink
Author: heocoi

@heocoi

About Mailsink

Programmatic temp email inboxes for QA tests and AI agents. 8 MCP tools, free tier 50 inboxes/month, MCP server published as @mailsink/mcp on npm.

#email #testing #automation #qa #mailsink #temp-email #otp #verification

Basic information

Config

Add this server to your MCP-compatible client using the configuration below.

{
  "mcpServers": {
    "mailsink": {
      "command": "npx",
      "args": [
        "-y",
        "@mailsink/mcp"
      ],
      "env": {
        "MAILSINK_API_KEY": "msk_..."
      }
    }
  }
}

Tools

Provision a throwaway address. Returns `email`, `id`, `expires_at`.

List active inboxes on the account.

Block up to `timeout` seconds (max 120) for any email to arrive.

Extract the most recent OTP from the inbox (polls until found or timeout).

Extract the most recent magic link.

Summaries of all messages in an inbox.

Full content of a specific message by ID.

Burn an inbox immediately.

Overview

What is Mailsink?

Mailsink is a Model Context Protocol (MCP) server that provides programmatic temporary email inboxes for AI agents and test automation. It gives agents eight typed tools for provisioning disposable addresses, waiting on signup emails, extracting OTP codes and magic links, and cleaning up after themselves. Works with Claude Code, Claude Desktop, Cursor, Windsurf, and any MCP-aware client.

How to use Mailsink?

Install globally via npm install -g @mailsink/mcp or run with npx -y @mailsink/mcp. Requires a free API key from mailsink.dev (exported as MAILSINK_API_KEY). Configure the client's mcpServers section with command npx and args ["-y", "@mailsink/mcp"] plus MAILSINK_API_KEY in env. Restart the client to see eight tools like create_inbox, wait_for_email, get_verification_code, etc.

Key features of Mailsink

Eight typed MCP tools for email workflow automation
Provision disposable inboxes with create_inbox
Wait for incoming emails with configurable timeout (up to 120s)
Extract OTP codes and magic links from received emails
List, read, and delete inboxes programmatically
No webhooks, IMAP, or MIME parsing required

Use cases of Mailsink

AI agent signs up for a service and captures a verification code or magic link
Test automation creates temporary inboxes, validates signup emails, and cleans up
Extract one-time passwords (OTPs) from signup or login emails automatically
Demo or integration testing requiring disposable email addresses

FAQ from Mailsink

What is the free tier and pricing?

Free tier includes 50 inboxes per month and MCP access. Pro ($15/mo) and Team ($49/mo) raise inbox caps, email size limits, TTL, and request rates.

How do I get an API key?

Sign in at mailsink.dev/app with GitHub, copy the one-time reveal key, and export it as MAILSINK_API_KEY environment variable.

What MCP clients are supported?

Claude Code, Claude Desktop, Cursor, and Windsurf, plus any other MCP-aware client.

What environment variables are required?

MAILSINK_API_KEY (required). Optionally MAILSINK_API_URL to override the default API endpoint.

How are emails fetched and how long can the server wait?

The wait_for_email tool blocks up to a configurable timeout (max 120 seconds) for any email to arrive. No persistent storage or webhook setup needed.