Add Mailloop
to

One plugin gives your coding agent a real email inbox, plus the skill that teaches it the testing workflow. Create sandboxes, wait for the email your app sends, and assert on it. Connect over OAuth in seconds. No API key to copy.

claude Run one at a time
/plugin marketplace add mailloop/skills
/plugin install mailloop@mailloop
  1. 1 Add the plugin Installs the tools and the skill.
  2. 2 Type /mcp Pick mailloop, choose Authenticate.
  3. 3 Sign in Approve in your browser. Done.
Using Cursor, VS Code or an API key? →

A few tools that cover the whole testing loop

#wait_for_email

Wait for an email to arrive

Block until a matching email lands in a sandbox. The one tool that makes end-to-end email testing work from an agent.

#create_sandbox

Create sandboxes on the fly

Spin up a fresh capture inbox for a test run, or list the ones you already have, without leaving the chat.

#create_temporary_sandbox

Create temporary sandboxes

Need a throwaway inbox for a single CI run? Create one that expires on its own, so nothing piles up.

#get_email

Inspect captured email

Read an email’s sanitized content and pull out every link, so the agent can follow a confirmation or reset flow.

#send_email

Send transactional email

Send block-based emails into a sandbox to test exactly what your app would deliver.

#create_webhook

Build and debug webhooks

Create, test, and inspect webhook deliveries end to end while you build the integration.

Install in your client

Claude Code connects over OAuth. Every other client works with a Bearer API key.

Then run /mcp in Claude Code and choose Authenticate. No API key needed. 
claude mcp add --transport http mailloop https://api.mailloop.io/mcp
Prefer a static key? Pass it as a header. Create one in Settings → Organization → API keys. 
claude mcp add --transport http mailloop https://api.mailloop.io/mcp \
  --header "Authorization: Bearer ml_live_xxx"

Connect over OAuth. No key to paste.

  1. Open Settings → Connectors → Add custom connector.
  2. Paste the URL https://api.mailloop.io/mcp and continue.
  3. Sign in to Mailloop and approve the organization and scopes.
Add to ~/.cursor/mcp.json. 
{
  "mcpServers": {
    "mailloop": {
      "url": "https://api.mailloop.io/mcp",
      "headers": { "Authorization": "Bearer ml_live_xxx" }
    }
  }
}
Uses an input prompt so your key never gets committed. 
{
  "inputs": [
    { "type": "promptString", "id": "mailloop-key", "description": "Mailloop API key", "password": true }
  ],
  "servers": {
    "mailloop": {
      "type": "http",
      "url": "https://api.mailloop.io/mcp",
      "headers": { "Authorization": "Bearer ${input:mailloop-key}" }
    }
  }
}
Note the serverUrl key (not url). 
{
  "mcpServers": {
    "mailloop": {
      "serverUrl": "https://api.mailloop.io/mcp",
      "headers": { "Authorization": "Bearer ml_live_xxx" }
    }
  }
}
Add to your Zed settings. 
{
  "context_servers": {
    "mailloop": {
      "url": "https://api.mailloop.io/mcp",
      "headers": { "Authorization": "Bearer ml_live_xxx" }
    }
  }
}

The tools, plus the playbook

The plugin you installed above ships two things. The MCP server gives your agent the tools. The skill teaches it how to run an email test: trigger the send, wait for the email, then check what arrived.

Only want the tools? Use the per-client setup above for the bare MCP server. The full playbook is in the Agent Skill docs.

See it in action

Ask in plain English. Your agent runs the whole test, step by step.

Signup testAwaiting first capture
Inbound address[email protected]
Hostsandbox.mailloop.io
Port2525
No activity yetOpen inbox →

Start testing emails today

Exhaustive SMTP sandbox, ready SDKs, and a full-featured inbox to help you test every email your app sends. GDPR compliant and EU-hosted.

Start for free View documentation