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io.github.heocoi/mailsink

Official registry Productivity

Disposable inboxes for AI agents and CI: catch the verification email, read the OTP or link.

Source code Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

NPM package @mailsink/mcp
Claude Code 
claude mcp add mailsink -e 'MAILSINK_API_KEY=<your mailsink_api_key>' -e 'MAILSINK_API_URL=<MAILSINK_API_URL>' -- npx -y @mailsink/mcp@0.1.5
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "mailsink": {
            "command": "npx",
            "args": [
                "-y",
                "@mailsink/mcp@0.1.5"
            ],
            "env": {
                "MAILSINK_API_KEY": "<your mailsink_api_key>",
                "MAILSINK_API_URL": "<MAILSINK_API_URL>"
            }
        }
    }
}

Environment variables

  • MAILSINK_API_KEY required secret Your MailSink API key. Get it at https://mailsink.dev/auth/github
  • MAILSINK_API_URL Optional API base URL override (defaults to https://api.mailsink.dev)

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. @mailsink/mcp
  2. Install
  3. Get an API key
  4. Configure your client
  5. Tools
  6. Example agent flow
  7. Environment variables
  8. Source
  9. License

@mailsink/mcp

Model Context Protocol server for MailSink — programmatic temporary email inboxes for AI agents and test automation.

Gives your agent eight typed tools for provisioning disposable addresses, waiting on signup emails, extracting OTP codes and magic links, and cleaning up after itself. Works in Claude Code, Claude Desktop, Cursor, Windsurf, and any other MCP-aware client.

Install

npm install -g @mailsink/mcp

Or run via npx without installing:

npx @mailsink/mcp

Get an API key

  1. Sign in at https://mailsink.dev/app with GitHub.
  2. Copy the key from the one-time reveal. Store it in your password manager or .env.
  3. Export it so the MCP server can read it:
     export MAILSINK_API_KEY="msk_..."

Free tier is 50 inboxes/month and includes MCP. Pro ($15/mo) and Team ($49/mo) lift the inbox cap, raise email size limits, extend TTL, and bump request rates. See pricing.

Configure your client

Claude Code
claude mcp add mailsink -- npx -y @mailsink/mcp
Claude Desktop / Cursor / Windsurf

Add to the mcpServers section of the client's config file:

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

Restart the client. You should see the mailsink server listed with its eight tools.

Tools

ToolPurpose
create_inboxProvision a throwaway address. Returns email, id, expires_at.
list_inboxesList active inboxes on the account.
wait_for_emailBlock up to timeout seconds (max 120) for any email to arrive.
get_verification_codeExtract the most recent OTP from the inbox (polls until found or timeout).
get_verification_linkExtract the most recent magic link.
list_messagesSummaries of all messages in an inbox.
get_messageFull content of a specific message by ID.
delete_inboxBurn an inbox immediately.

Example agent flow

> Sign me up for Figma, capture the verification code, confirm, and
> tell me the plan once you're in.

[agent invokes]
  create_inbox()                                → agent@codenotify.net
  [agent fills the Figma signup form with that address]
  wait_for_email(inbox_id)                      → blocks 30s…
                                                → returns email + OTP
  [agent types the OTP into the Figma form]
  delete_inbox(inbox_id)                        → cleanup

No webhook plumbing. No IMAP credentials. No parsing MIME.

Environment variables

  • MAILSINK_API_KEY (required) — your account's API key.
  • MAILSINK_API_URL (optional, default https://api.mailsink.dev) — override for self-hosted or dev API.

Source

https://github.com/heocoi/mailsink/tree/main/mcp

License

MIT — see LICENSE.

Frequently asked questions

What is io.github.heocoi/mailsink?

Disposable inboxes for AI agents and CI: catch the verification email, read the OTP or link.

How do I install io.github.heocoi/mailsink?

It runs on your machine. In Claude Code: claude mcp add mailsink -e 'MAILSINK_API_KEY=<your mailsink_api_key>' -e 'MAILSINK_API_URL=<MAILSINK_API_URL>' -- npx -y @mailsink/mcp@0.1.5. For other clients, paste the JSON configuration from this page into their MCP settings.

Does io.github.heocoi/mailsink need an API key?

Yes. It expects MAILSINK_API_KEY, which you set in its configuration.

Is io.github.heocoi/mailsink open source?

Yes. Its code is on GitHub under the MIT license.

Who maintains io.github.heocoi/mailsink?

It is published by heocoi. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.