MailerCheck MCP server for AI agents and assistants

Securely connect your AI agents and chatbots (Claude, ChatGPT, Cursor, etc) with MailerCheck MCP or direct API to verify email addresses, validate email lists, review verification results, and monitor account credits through natural language.

MailerCheck logoMailerCheck
Api Key

MailerCheck is an email verification service for checking addresses and lists. It helps protect sender reputation by reducing bounces and bad contacts.

9 Tools

Try MailerCheck now

Type what you want done — sign in and watch it run live in the Tool Router playground.

TOOL ROUTER PLAYGROUND
MailerCheck
Try asking
TOOLS

Supported Tools

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

Create Verification List

Create a MailerCheck verification list by ingesting a name and email-address array.

Delete Verification List

Permanently and irreversibly delete a MailerCheck verification list by ID.

Get Credit Balance

Return the current MailerCheck verification-credit balance.

Get Current Account

Return the connected MailerCheck user and account identity.

Get Verification List

Return one verification list, including its status, item count, verification timing, and aggregate result statistics.

List Verification Lists

Return one page of verification lists for the connected MailerCheck account, with an opaque cursor when another provider-controlled page exists.

List Verification Results

Return one page of email-level results for a verification list, optionally filtered by classification.

Start List Verification

Irreversibly start verification of every address in a MailerCheck list.

Verify Email

Consumes exactly one MailerCheck verification credit on every successful call.

SETUP GUIDE

Connect MailerCheck MCP Tool with your Agent

1

Install Composio

typescript
npm install @composio/core ai @ai-sdk/mcp @ai-sdk/openai
Install the Composio SDK and your agent framework
2

Create a session with MCP enabled

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

const composio = new Composio();
const { mcp } = await composio.create("your-user-id", {
  toolkits: ["mailercheck"],
  mcp: true,
});
Create a session scoped to MailerCheck and read its MCP URL and headers
3

Connect your agent to the MCP server

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 the email address lead@example.com with MailerCheck and report the status.",
  stopWhen: stepCountIs(10),
});

console.log(text);
await client.close();
Pass the session's MCP URL and headers to your agent and run a MailerCheck request
SETUP GUIDE

Connect MailerCheck API Tool with your Agent

1

Install Composio

typescript
npm install @composio/core @composio/openai openai
Install the Composio SDK, the OpenAI provider, and the OpenAI SDK
2

Create a Composio session

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: ["mailercheck"] });
const tools = await session.tools();
Initialize Composio with the OpenAI Responses provider and create a session scoped to MailerCheck
3

Run MailerCheck tools with your agent

typescript
let response = await client.responses.create({
  model: "gpt-5.6-sol",
  tools,
  input: [{ role: "user", content: "Verify the email address lead@example.com with MailerCheck and report the status." }],
});

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);
Send a request, execute the MailerCheck tool calls through the session, and print the final answer

Why Use Composio?

AI Native MailerCheck Integration

  • Supports both MailerCheck MCP and direct API based integrations
  • Structured, LLM-friendly schemas for reliable email verification workflows
  • Rich coverage for checking single emails, validating lists, reading reports, and tracking credits

Managed Auth

  • Secure API key handling without hard-coding MailerCheck credentials in your agent code
  • Central place to manage, scope, and revoke MailerCheck access
  • Per user and per environment credentials for cleaner, safer deployments

Agent Optimized Design

  • Tools are tuned so agents can reliably verify addresses and explain MailerCheck results
  • Comprehensive execution logs so you always know which email was checked, when, and on whose behalf
  • Works with auth_configs.create(), connected_accounts.link(), and mcp.create() when you need deeper setup control

Enterprise Grade Security

  • Fine-grained RBAC so you control which agents and users can access MailerCheck
  • Scoped, least privilege access to MailerCheck verification and credit data
  • Full audit trail of agent actions to support review and compliance
FAQ

Frequently asked questions

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

Yes! Composio's Tool Router enables agents to use multiple toolkits. Learn more.

Yes. Composio is SOC 2 Type II compliant and is built to keep your MailerCheck connection and credentials secure. OAuth tokens and API keys are encrypted, and sensitive customer data is protected at rest and in transit.

Composio also undergoes independent security testing and continuously monitors its systems for security threats. You can review the latest reports and policies in the Composio Trust Center.

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

Create the key in your MailerCheck account settings, then paste it once on Composio's connection page. Composio stores it encrypted and uses it only for the MailerCheck actions your agent runs. Nobody else in your workspace can read it, and you can revoke it inside MailerCheck at any time.

When you connect a MailerCheck account through Composio, every action runs under that account, so anything the agent creates, sends, or changes shows up in MailerCheck as done by you. Keep an approval step in your prompt for actions with side effects, such as sending or deleting, and have the agent draft first.

Whatever the credentials you connect allow inside MailerCheck. If MailerCheck lets you scope a key to specific permissions, create a scoped one so the agent can only do what you intend. You can revoke the key inside MailerCheck at any time.

Yes. Composio supports multiple connected accounts for the same app, and that works in Claude, ChatGPT, or any other assistant you connect through Composio. Give each MailerCheck connection a name such as work or personal, and the assistant uses the one you mention in the request. Each account keeps its own credentials and nothing is merged.

The connection stops working the moment MailerCheck rejects the old key. Create a new key in MailerCheck and reconnect the account from the Composio dashboard or by asking your agent to reconnect MailerCheck. Nothing else changes.

Composio's free Hobby plan includes 100,000 tool calls per month with no credit card, which covers most personal MailerCheck use. Paid plans add higher limits and team features. Your MailerCheck plan and its API limits still apply as usual.

Built-in connectors usually give one AI access to a limited set of apps. Many people use Composio because it lets their AI connect to more apps than it normally supports, or connect to multiple accounts for the same app (e.g. connect Claude to multiple MailerCheck accounts).

With Composio, you connect MailerCheck once and then use it across different AI assistants without setting it up separately in each one. Connect your apps to Composio once, then connect Composio to whichever AI you use, whether that's Claude, ChatGPT, Hermes, or your own custom assistant.

Start with MailerCheck.It takes 30 seconds.

Managed auth, hosted MCP servers, and every MailerCheck tool your agent needs.Free to start.

Start building