# How to integrate Mails so MCP with Codex

```json
{
  "title": "How to integrate Mails so MCP with Codex",
  "toolkit": "Mails so",
  "toolkit_slug": "mails_so",
  "framework": "Codex",
  "framework_slug": "codex",
  "url": "https://composio.dev/toolkits/mails_so/framework/codex",
  "markdown_url": "https://composio.dev/toolkits/mails_so/framework/codex.md",
  "updated_at": "2026-05-12T10:18:21.496Z"
}
```

## Introduction

Codex is one of the most popular coding harnesses out there. And MCP makes the experience even better. With Mails so MCP integration, you can draft, triage, summarise emails, and much more, all without leaving the terminal or the app, whichever you prefer.

## Also integrate 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)
- [OpenClaw](https://composio.dev/toolkits/mails_so/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/mails_so/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/mails_so/framework/cli)
- [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)

## TL;DR

### Why use Composio?
Apart from a managed and hosted MCP server, you will get:
- CodeAct: A dedicated workbench that allows GPT to write its code to handle complex tool chaining. Reduces to-and-fro with LLMs for frequent tool calling.
- Large tool responses: Handle them to minimise context rot.
- Dynamic just-in-time access to 20,000 tools across 1000+ other Apps for cross-app workflows. It loads the tools you need, so GPTs aren't overwhelmed by tools you don't need.

## Connect Mails so to Codex

### How to install Mails so MCP in Codex
### Run the setup command
Run this command in your terminal to add the Composio MCP server to Codex.

```bash
codex mcp add composio --url https://connect.composio.dev/mcp
```

## What is the Mails so MCP server, and what's possible with it?

The Mails so MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Mails so account. It provides structured and secure access to advanced email validation services, so your agent can perform actions like verifying single emails, running bulk checks, and retrieving validation results on your behalf.
- Single email validation: Instantly check if an individual email address is valid and safe to use before sending important messages.
- Bulk email validation: Submit large lists of email addresses for automated deliverability and quality checks, keeping your contact databases clean.
- Batch results retrieval: Effortlessly fetch detailed validation outcomes for previously submitted bulk jobs, so you can review and act on the results.
- Email list hygiene automation: Use the agent to regularly scan and validate contact lists, reducing bounce rates and improving sender reputation.

## 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.

## Creating MCP Server - Stand-alone vs Composio SDK

The Mails so MCP server provides comprehensive access to Mails so operations through Composio. Once connected, you can perform all major Mails so actions directly from Codex using natural language commands.

## Complete Code

None listed.

## Conclusion

### Conclusion
You've successfully integrated Mails so with Codex using Composio's MCP server. Now you can interact with Mails so directly from your terminal, VS Code, or the Codex App using natural language commands.
Key benefits of this setup:
- Seamless integration across CLI, VS Code, and standalone app
- Natural language commands for Mails so operations
- Managed authentication through Composio
- Access to 20,000+ tools across 1000+ apps for cross-app workflows
- CodeAct workbench for complex tool chaining
Next steps:
- Try asking Codex to perform various Mails so operations
- Explore cross-app workflows by connecting more toolkits
- Build automation scripts that leverage Codex's AI capabilities

## How to build Mails so MCP Agent with another framework

- [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)
- [OpenClaw](https://composio.dev/toolkits/mails_so/framework/openclaw)
- [Hermes](https://composio.dev/toolkits/mails_so/framework/hermes-agent)
- [CLI](https://composio.dev/toolkits/mails_so/framework/cli)
- [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)

## Related Toolkits

- [Reddit](https://composio.dev/toolkits/reddit) - Reddit is a social news platform with thriving user-driven communities (subreddits). It's the go-to place for discussion, content sharing, and viral marketing.
- [Facebook](https://composio.dev/toolkits/facebook) - Facebook is a social media and advertising platform for businesses and creators. It helps you connect, share, and manage content across your public Facebook Pages.
- [Linkedin](https://composio.dev/toolkits/linkedin) - LinkedIn is a professional networking platform for connecting, sharing content, and engaging with business opportunities. It's the go-to place for building your professional brand and unlocking new career connections.
- [Active campaign](https://composio.dev/toolkits/active_campaign) - ActiveCampaign is a marketing automation and CRM platform for managing email campaigns, sales pipelines, and customer segmentation. It helps businesses engage customers and drive growth through smart automation and targeted outreach.
- [ActiveTrail](https://composio.dev/toolkits/active_trail) - ActiveTrail is a user-friendly email marketing and automation platform. It helps you reach subscribers and automate campaigns with ease.
- [Ahrefs](https://composio.dev/toolkits/ahrefs) - Ahrefs is an SEO and marketing platform for site audits, keyword research, and competitor insights. It helps you improve search rankings and drive organic traffic.
- [Amcards](https://composio.dev/toolkits/amcards) - AMCards lets you create and mail personalized greeting cards online. Build stronger customer relationships with easy, automated card campaigns.
- [Beamer](https://composio.dev/toolkits/beamer) - Beamer is a news and changelog platform for in-app announcements and feature updates. It helps companies boost user engagement by sharing news where users are most active.
- [Benchmark email](https://composio.dev/toolkits/benchmark_email) - Benchmark Email is a platform for creating, sending, and tracking email campaigns. It's built to help you engage audiences and analyze results—all in one place.
- [Bigmailer](https://composio.dev/toolkits/bigmailer) - BigMailer is an email marketing platform for managing multiple brands with white-labeling and automation. It helps teams streamline campaigns and simplify integration with Amazon SES.
- [Brandfetch](https://composio.dev/toolkits/brandfetch) - Brandfetch is an API that delivers company logos, colors, and visual branding assets. It helps marketers and developers keep brand visuals consistent everywhere.
- [Brevo](https://composio.dev/toolkits/brevo) - Brevo is an all-in-one email and SMS marketing platform for transactional messaging, automation, and CRM. It helps businesses engage customers and streamline communications through powerful campaign tools.
- [Campayn](https://composio.dev/toolkits/campayn) - Campayn is an email marketing platform for creating, sending, and managing campaigns. It helps businesses engage contacts and grow audiences with easy-to-use tools.
- [Cardly](https://composio.dev/toolkits/cardly) - Cardly is a platform for creating and sending personalized direct mail to customers. It helps businesses break through the digital clutter by getting real engagement via physical mailboxes.
- [ClickSend](https://composio.dev/toolkits/clicksend) - ClickSend is a cloud-based SMS and email marketing platform for businesses. It streamlines communication by enabling quick message delivery and contact management.
- [Crustdata](https://composio.dev/toolkits/crustdata) - CrustData is an AI-powered data intelligence platform for real-time company and people data. It helps B2B sales teams, AI SDRs, and investors react to live business signals.
- [Curated](https://composio.dev/toolkits/curated) - Curated is a platform for collecting, curating, and publishing newsletters. It streamlines content aggregation and distribution for creators and teams.
- [Customerio](https://composio.dev/toolkits/customerio) - Customer.io is a customer engagement platform for targeted messaging across email, SMS, and push. Easily automate, segment, and track communications with your audience.
- [Cutt ly](https://composio.dev/toolkits/cutt_ly) - Cutt.ly is a URL shortening service for managing and analyzing links. Streamline your workflows with quick, trackable, and branded short URLs.
- [Demio](https://composio.dev/toolkits/demio) - Demio is webinar software built for marketers, offering both live and automated sessions with interactive features. It helps teams engage audiences and optimize lead generation through detailed analytics.

## Frequently Asked Questions

### What are the differences in Tool Router MCP and Mails so MCP?

With a standalone Mails so MCP server, the agents and LLMs can only access a fixed set of Mails so tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Mails so and many other apps based on the task at hand, all through a single MCP endpoint.

### Can I use Tool Router MCP with Codex?

Yes, you can. Codex fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Mails so tools.

### Can I manage the permissions and scopes for Mails so while using Tool Router?

Yes, absolutely. You can configure which Mails so scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

### How safe is my data with Composio Tool Router?

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Mails so data and credentials are handled as safely as possible.

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