# MailboxValidator

```json
{
  "name": "MailboxValidator",
  "slug": "mailboxvalidator",
  "url": "https://composio.dev/toolkits/mailboxvalidator",
  "markdown_url": "https://composio.dev/toolkits/mailboxvalidator.md",
  "logo_url": "https://logos.composio.dev/api/mailboxvalidator",
  "categories": [
    "developer tools & devops"
  ],
  "is_composio_managed": false,
  "updated_at": "2026-10-04T18:12:09.098Z"
}
```

![MailboxValidator logo](https://logos.composio.dev/api/mailboxvalidator)

## Description

Securely connect your AI agents and chatbots (Claude, ChatGPT, Cursor, etc) with MailboxValidator MCP or direct API to verify email addresses, check deliverability and SMTP status, detect disposable providers, and run bulk validations through natural language.

## Summary

MailboxValidator is an email verification service that checks syntax, deliverability, mail-server availability, and disposable provider status.
Use it to reduce bounces, catch disposable addresses, and improve overall email deliverability.

## Categories

- developer tools & devops

## Toolkit Details

- Tools: 3

## Images

- Logo: https://logos.composio.dev/api/mailboxvalidator

## Authentication

- **Api Key**
  - Type: `api_key`
  - Description: Api Key authentication for MailboxValidator.
  - Setup:
    - Configure Api Key credentials for MailboxValidator.
    - Use the credentials when creating an auth config in Composio.

## Suggested Prompts

- Verify 100 email addresses from CSV
- Identify disposable addresses in my list
- Check SMTP deliverability for support@example.com

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `MAILBOXVALIDATOR_CHECK_DISPOSABLE_EMAIL` | Check Disposable Email | Check whether one email address uses a disposable email provider. Consumes one API credit. |
| `MAILBOXVALIDATOR_CHECK_FREE_EMAIL` | Check Free Email | Check whether one email address uses a free email provider. Consumes one API credit. |
| `MAILBOXVALIDATOR_VALIDATE_EMAIL` | Validate Email | Run comprehensive syntax, domain, mail-server, reputation, and provider checks on one email address. The status field is the overall validation verdict; an HTTP success alone does not mean the mailbox was verified. Consumes one API credit. |

## Supported Triggers

None listed.

## Installation and MCP Setup

### Path 1: SDK Installation

#### Path 1, Step 1: Install Composio

Install the Composio SDK, the OpenAI provider, and the OpenAI SDK
```python
pip install composio composio_openai openai
```

```typescript
npm install @composio/core @composio/openai openai
```

#### Path 1, Step 2: Create a Composio session

Initialize Composio with the OpenAI Responses provider and create a session scoped to MailboxValidator
```python
import json
from openai import OpenAI
from composio import Composio
from composio_openai import OpenAIResponsesProvider

composio = Composio(provider=OpenAIResponsesProvider())
client = OpenAI()

session = composio.create(user_id="your-user-id", toolkits=["mailboxvalidator"])
tools = session.tools()
```

```typescript
import OpenAI from "openai";
import { Composio } from "@composio/core";
import { OpenAIResponsesProvider } from "@composio/openai";

const composio = new Composio({ provider: new OpenAIResponsesProvider() });
const client = new OpenAI();

const session = await composio.create("your-user-id", { toolkits: ["mailboxvalidator"] });
const tools = await session.tools();
```

#### Path 1, Step 3: Run MailboxValidator tools with your agent

Send a request, execute the MailboxValidator tool calls through the session, and print the final answer
```python
response = client.responses.create(
    model="gpt-5.6-sol",
    tools=tools,
    input=[{"role": "user", "content": "Verify 100 email addresses from CSV"}],
)

while True:
    tool_calls = [o for o in response.output if o.type == "function_call"]
    if not tool_calls:
        break
    results = composio.provider.handle_tool_calls(response=response, session=session)
    response = client.responses.create(
        model="gpt-5.6-sol",
        tools=tools,
        previous_response_id=response.id,
        input=[
            {"type": "function_call_output", "call_id": call.call_id, "output": json.dumps(results[i])}
            for i, call in enumerate(tool_calls)
        ],
    )

print(response.output_text)
```

```typescript
let response = await client.responses.create({
  model: "gpt-5.6-sol",
  tools,
  input: [{ role: "user", content: "Verify 100 email addresses from CSV" }],
});

while (response.output.some((o) => o.type === "function_call")) {
  const outputs = await composio.provider.handleToolCalls(session, response.output);
  response = await client.responses.create({
    model: "gpt-5.6-sol",
    tools,
    previous_response_id: response.id,
    input: outputs,
  });
}

console.log(response.output_text);
```

### Path 2: MCP Server Setup

#### Path 2, Step 1: Install Composio

Install the Composio SDK and your agent framework
```python
pip install composio claude-agent-sdk
```

```typescript
npm install @composio/core ai @ai-sdk/mcp @ai-sdk/openai
```

#### Path 2, Step 2: Create a session with MCP enabled

Create a session scoped to MailboxValidator and read its MCP URL and headers
```python
from composio import Composio

composio = Composio()
session = composio.create(user_id="your-user-id", toolkits=["mailboxvalidator"], mcp=True)
```

```typescript
import { Composio } from "@composio/core";

const composio = new Composio();
const { mcp } = await composio.create("your-user-id", {
  toolkits: ["mailboxvalidator"],
  mcp: true,
});
```

#### Path 2, Step 3: Connect your agent to the MCP server

Pass the session's MCP URL and headers to your agent and run a MailboxValidator request
```python
import asyncio
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions, AssistantMessage, TextBlock

options = ClaudeAgentOptions(
    mcp_servers={
        "composio": {
            "type": "http",
            "url": session.mcp.url,
            "headers": session.mcp.headers,
        }
    },
    system_prompt="You are a helpful assistant with access to MailboxValidator tools.",
    tools=[],
    allowed_tools=["mcp__composio__*"],
)

async def main():
    async with ClaudeSDKClient(options=options) as client:
        await client.query("Verify 100 email addresses from CSV")
        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, TextBlock):
                        print(block.text)

asyncio.run(main())
```

```typescript
import { createMCPClient } from "@ai-sdk/mcp";
import { openai } from "@ai-sdk/openai";
import { generateText, stepCountIs } from "ai";

const client = await createMCPClient({
  transport: { type: "http", url: mcp.url, headers: mcp.headers },
});

const { text } = await generateText({
  model: openai("gpt-5.6-sol"),
  tools: await client.tools(),
  prompt: "Verify 100 email addresses from CSV",
  stopWhen: stepCountIs(10),
});

console.log(text);
await client.close();
```

## Why Use Composio?

### 1. AI Native MailboxValidator Integration

- Supports both MailboxValidator MCP and direct API based integrations
- Structured, LLM-friendly schemas for reliable tool execution
- Rich coverage for reading, writing, and querying your MailboxValidator data

### 2. Managed Auth

- Built-in OAuth handling with automatic token refresh and rotation
- Central place to manage, scope, and revoke MailboxValidator access
- Per user and per environment credentials instead of hard-coded keys

### 3. Agent Optimized Design

- Tools are tuned using real error and success rates to improve reliability over time
- Comprehensive execution logs so you always know what ran, when, and on whose behalf

### 4. Enterprise Grade Security

- Fine-grained RBAC so you control which agents and users can access MailboxValidator
- Scoped, least privilege access to MailboxValidator resources
- Full audit trail of agent actions to support review and compliance

## Use MailboxValidator with any AI Agent Framework

Choose a framework you want to connect MailboxValidator with:

- [ChatGPT](https://composio.dev/toolkits/mailboxvalidator/framework/chatgpt)
- [Claude Cowork](https://composio.dev/toolkits/mailboxvalidator/framework/claude-cowork)
- [Hermes](https://composio.dev/toolkits/mailboxvalidator/framework/hermes-agent)
- [Atomic Agent](https://composio.dev/toolkits/mailboxvalidator/framework/atomic-agent)

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## Frequently Asked Questions

### Do I need my own developer credentials to use MailboxValidator with Composio?

Yes, MailboxValidator requires you to configure your own API key credentials. Once set up, Composio handles secure credential storage and API request handling for you.

### Can I use multiple toolkits together?

Yes! Composio's Tool Router enables agents to use multiple toolkits. [Learn more](https://docs.composio.dev/tool-router/overview).

### Is Composio secure?

Composio is SOC 2 and ISO 27001 compliant with all data encrypted in transit and at rest. [Learn more](https://trust.composio.dev).

### What if the API changes?

Composio maintains and updates all toolkit integrations automatically, so your agents always work with the latest API versions.

---
[See all toolkits](https://composio.dev/toolkits) · [Composio docs](https://docs.composio.dev/llms.txt)