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How to integrate SMTPing MCP with Atomic Agent

Connect Atomic Agent to SMTPing MCP. Verify an email address before sending, check an address against threat lists, and more using natural language, with authentication handled for you.

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SMTPing

Api Key

SMTPing is an email verification service for validating addresses, checking threat lists, and monitoring account usage. It helps teams reduce bounced emails and protect sender reputation.

14 Tools

Managed auth

Connect SMTPing without auth hassles

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Introduction

Atomic Agent is an open-source AI agent that runs on your machine and supports local models through llama.cpp. Connect it to 1,500+ apps through Composio, including SMTPing.

This guide uses Atomic Agent's built-in Composio integration. You need Atomic Agent v0.5.6 or later, your own Composio API key, and a SMTPing account. See the Atomic Agent documentation for installation instructions.

Also integrate SMTPing with

ChatGPT Claude Cowork Hermes

How Atomic Agent connects to SMTPing

Atomic Agent connects to Composio's Tool Router over Streamable HTTP MCP. It discovers the tools needed for your request, and Composio handles account authentication.

Execution and account-connection tools follow Atomic Agent's configured approval policy. Review any approval prompt before allowing an action on your connected account.

Connect SMTPing to Atomic Agent

Sign up or sign in to the Composio dashboard. Copy your API key.
In Atomic Agent, open the Integrations tab and select Composio. Select API key, press e, paste the key, and press Enter. The tools become available immediately, without a restart.
Ask Atomic Agent to do something in SMTPing. It searches Composio for the right tool.
On first use, open the sign-in link returned in the chat. Connect your SMTPing account, then return to Atomic Agent to continue.

Headless setup

Add the following line to ~/.atomic-agent/.env, replacing YOUR_COMPOSIO_API_KEY with your key. Start Atomic Agent after saving the file.

bash

COMPOSIO_API_KEY=YOUR_COMPOSIO_API_KEY

What is the SMTPing MCP server, and what's possible with it?

The SMTPing MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your SMTPing account. It provides structured and secure access to email verification, threat-list checks, bulk jobs, credits, and usage data, so your agent can verify addresses, identify risky emails, process large lists, monitor credits, and review API usage on your behalf.

Email address verification: Have your agent verify individual email addresses and review their deliverability status and domain flags.
Threat-list screening: Direct your agent to check an email or a batch of up to 1,000 addresses against a selected SMTPing threat list.
Bulk email processing: Instruct your agent to start large verification or threat-list jobs for up to 100,000 addresses, then check progress and retrieve the results.
Risk and domain flag checks: Let the agent inspect all six SMTPing risk and domain flags for a specific email address.
Credits and usage tracking: Have your agent check remaining credits, review aggregate usage, list recent API requests, or export usage history as a CSV file.

Use SMTPing from Atomic Agent

With your account connected, ask Atomic Agent to work with SMTPing in natural language. You can connect more apps through the same Composio integration as you need them.

Visit the Atomic Agent website or inspect the Atomic Agent source code.

Troubleshooting

Why is my API key rejected?

Copy the key directly from the Composio dashboard. Atomic Agent requires ASCII characters because it sends the key in an HTTP header. Remove any extra characters introduced when copying.

Why are Composio tools unavailable after saving a key?

Check that you use Atomic Agent v0.5.6 or later and that Composio is enabled in your configuration. A "composio": { "enabled": false } setting disables the integration while keeping the saved key on disk.

Does Composio have a free plan?

The Hobby plan includes 100,000 tool calls per month. Composio-managed OAuth apps have a lower included allowance. See Composio pricing for the current limits that apply to your connection.

TOOLS

Supported Tools

Every SMTPing action and event your agent gets out of the box.

Check Email

Check one email address against one selected SMTPing threat list and report whether it matched.

Check Email Batch

Synchronously check 1 to 1,000 email addresses against one selected SMTPing threat list and return all results.

Check Email Flags

Return all six SMTPing risk and domain flags for one email address in one request.

Create Bulk Check Job

Start an asynchronous SMTPing threat-list check for 1 to 100,000 email addresses.

Create Bulk Verification Job

Start asynchronous verification for 1 to 100,000 email addresses and return the job ID to use for status polling and result retrieval.

Export Usage

Download SMTPing usage history as a CSV file for the provider's default date range.

Get Bulk Check Job

Get progress and match counts for an asynchronous threat-list check job.

Get Bulk Check Results

Return all address-level matches for a bulk threat-list check job after its status is Succeeded or Completed.

Get Bulk Verification Job

Get progress and summary counts for an asynchronous bulk verification job.

Get Bulk Verification Results

Return all address-level results for a bulk verification job after its status is Succeeded.

Get Credits

Return the connected account's current credit balance, plan, and daily remaining credits.

Get Usage

Return aggregate request, email, credit, status, endpoint, and error usage for SMTPing's current default date range.

List Usage Requests

Return the newest available page of individual SMTPing API request history, up to the provider default of 50 rows, with page metadata.

Verify Email

Verify one email address and return its deliverability status and domain flags.

FRAMEWORKS

How to build SMTPing MCP Agent with another framework

ChatGPT

Use SMTPing MCP with ChatGPT

Claude Cowork

Use SMTPing MCP with Claude Cowork

Hermes

Use SMTPing MCP with Hermes

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FAQ

Frequently asked questions

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

Yes, you can. Atomic Agent 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 SMTPing tools.

Yes, absolutely. You can configure which SMTPing 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.

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 SMTPing data and credentials are handled as safely as possible.

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