# Mails so

```json
{
  "name": "Mails so",
  "slug": "mails_so",
  "url": "https://composio.dev/toolkits/mails_so",
  "markdown_url": "https://composio.dev/toolkits/mails_so.md",
  "logo_url": "https://logos.composio.dev/api/mails_so",
  "categories": [
    "marketing & social media"
  ],
  "is_composio_managed": false,
  "updated_at": "2026-05-12T10:18:21.496Z"
}
```

![Mails so logo](https://logos.composio.dev/api/mails_so)

## Description

Securely connect your AI agents and chatbots (Claude, ChatGPT, Cursor, etc) with Mails so MCP or direct API to validate email addresses, check inbox quality, identify risky contacts, and automate bulk email list cleaning through natural language.

## Summary

Mails so is an API service for email validation and verification. It helps you keep your contact lists clean, accurate, and free from invalid or risky addresses.

## Categories

- marketing & social media

## Toolkit Details

- Tools: 3

## Images

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

## Authentication

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

## Suggested Prompts

- Check if this email address is valid
- Validate a list of emails before campaign
- Download results for last batch validation job
- Verify deliverability of new newsletter signups

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `MAILS_SO_RETRIEVE_BATCH_RESULTS` | Retrieve Batch Results | Tool to retrieve results of a bulk validation job. Use after submitting a batch and you have its ID. |
| `MAILS_SO_VALIDATE_BULK_EMAILS` | Validate Bulk Emails | Tool to validate multiple email addresses in bulk. Use when you need to confirm deliverability of a list of emails at once. |
| `MAILS_SO_VALIDATE_SINGLE_EMAIL` | Validate Single Email | Tool to validate a single email address. Use when you need to check deliverability and quality details before sending an email. |

## Supported Triggers

None listed.

## Installation and MCP Setup

### Path 1: SDK Installation

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

Install the Composio SDK
```python
pip install composio_openai
```

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

#### Path 1, Step 2: Initialize Composio and Create Tool Router Session

Import and initialize Composio client, then create a Tool Router session
```python
from openai import OpenAI
from composio import Composio
from composio_openai import OpenAIResponsesProvider

composio = Composio(provider=OpenAIResponsesProvider())
openai = OpenAI()
session = composio.create(user_id='your-user-id')
```

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

const composio = new Composio({
  provider: new OpenAIResponsesProvider(),
});
const openai = new OpenAI({});
const session = await composio.create('your-user-id');
```

#### Path 1, Step 3: Execute Mails so Tools via Tool Router with Your Agent

Get tools from Tool Router session and execute Mails so actions with your Agent
```python
tools = session.tools
response = openai.responses.create(
  model='gpt-4.1',
  tools=tools,
  input=[{
    'role': 'user',
    'content': 'Validate a list of emails before a campaign'
  }]
)
result = composio.provider.handle_tool_calls(
  response=response,
  user_id='your-user-id'
)
print(result)
```

```typescript
const tools = session.tools;
const response = await openai.responses.create({
  model: 'gpt-4.1',
  tools: tools,
  input: [{
    role: 'user',
    content: 'Validate a list of emails before a campaign'
  }],
});
const result = await composio.provider.handleToolCalls(
  'your-user-id',
  response.output
);
console.log(result);
```

### Path 2: MCP Server Setup

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

Install the Composio SDK and Claude Agent SDK
```python
pip install composio claude-agent-sdk
```

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

#### Path 2, Step 2: Create Tool Router Session

Initialize the Composio client and create a Tool Router session
```python
from composio import Composio
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions

composio = Composio(api_key='your-composio-api-key')
session = composio.create(user_id='your-user-id')
url = session.mcp.url
```

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

const composio = new Composio({ apiKey: 'your-api-key' });

console.log("Creating Tool Router session...");
const { mcp } = await composio.create('your-user-id');
console.log(`Tool Router session created: ${mcp.url}`);
```

#### Path 2, Step 3: Connect to AI Agent

Use the MCP server with your AI agent
```python
import asyncio

options = ClaudeAgentOptions(
    permission_mode='bypassPermissions',
    mcp_servers={
        'tool_router': {
            'type': 'http',
            'url': url,
            'headers': {
                'x-api-key': 'your-composio-api-key'
            }
        }
    },
    system_prompt='You are a helpful assistant with access to Mails so tools.',
    max_turns=10
)

async def main():
    async with ClaudeSDKClient(options=options) as client:
        await client.query('Validate these emails: john@example.com, jane@sample.org, invalid@bad.com')
        async for message in client.receive_response():
            if hasattr(message, 'content'):
                for block in message.content:
                    if hasattr(block, 'text'):
                        print(block.text)

asyncio.run(main())
```

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

const client = await createMCPClient({
  transport: {
    type: 'http',
    url: mcp.url,
    headers: { 'x-api-key': 'your-composio-api-key' }
  }
});

const tools = await client.tools();

const { text } = await generateText({
  model: openai('gpt-4o'),
  tools,
  messages: [{ role: 'user', content: 'Validate these emails: john@example.com, jane@sample.org, invalid@bad.com' }],
  stopWhen: stepCountIs(5)
});

console.log(`Agent: ${text}`);
```

## Why Use Composio?

### 1. AI Native Mails so Integration

- Supports both Mails so MCP and direct API based integrations
- Structured, LLM-friendly schemas for reliable tool execution
- Rich coverage for validating, cleansing, and querying your email lists

### 2. Managed Auth

- Built-in API key management for Mails so—no manual secrets rotation
- Central place to manage, scope, and revoke Mails so 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 Mails so
- Scoped, least privilege access to email validation actions
- Full audit trail of agent actions to support review and compliance

## Use Mails so with any AI Agent Framework

Choose a framework you want to connect Mails so with:

- [OpenAI Agents SDK](https://composio.dev/toolkits/mails_so/framework/open-ai-agents-sdk)
- [Claude Agent SDK](https://composio.dev/toolkits/mails_so/framework/claude-agents-sdk)
- [Claude Code](https://composio.dev/toolkits/mails_so/framework/claude-code)
- [Claude Cowork](https://composio.dev/toolkits/mails_so/framework/claude-cowork)
- [Codex](https://composio.dev/toolkits/mails_so/framework/codex)
- [OpenClaw](https://composio.dev/toolkits/mails_so/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/mails_so/framework/hermes-agent)
- [Google ADK](https://composio.dev/toolkits/mails_so/framework/google-adk)
- [LangChain](https://composio.dev/toolkits/mails_so/framework/langchain)
- [Vercel AI SDK](https://composio.dev/toolkits/mails_so/framework/ai-sdk)
- [Mastra AI](https://composio.dev/toolkits/mails_so/framework/mastra-ai)
- [LlamaIndex](https://composio.dev/toolkits/mails_so/framework/llama-index)
- [CrewAI](https://composio.dev/toolkits/mails_so/framework/crew-ai)
- [Pydantic AI](https://composio.dev/toolkits/mails_so/framework/pydantic-ai)
- [AutoGen](https://composio.dev/toolkits/mails_so/framework/autogen)

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## Frequently Asked Questions

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

Yes, Mails so 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)