mailfloss MCP server for AI agents and assistants

Securely connect your AI agents and chatbots (Claude, ChatGPT, Cursor, etc) with mailfloss MCP or direct API to verify email addresses, submit batch checks, track verification jobs, and review results through natural language.

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Api Key

mailfloss is an email verification service with APIs for checking addresses and processing verification batches. It helps teams reduce invalid contacts and keep email lists clean.

12 Tools

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

TOOL ROUTER PLAYGROUND
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TOOLS

Supported Tools

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

Cancel Batch Verification

Cancel a pending or in-progress batch verification job.

Check API Key

Verify that the connected Mailfloss API key is valid.

Create Batch Verification

Submit email addresses for asynchronous batch verification and return the job ID.

Erase Verification Records

Permanently erase stored verification records for the supplied email addresses.

Get Account

Return the authenticated Mailfloss account holder's identity, contact details, security posture, notification preferences, and signup time.

Get Batch Verification Results

Return one cursor-controlled page of stored batch results after organization floss-setting overrides.

Get Batch Verification Status

Read an asynchronous batch verification job's state and available counters.

Get Verification Job

Return one verification job and its complete verdict breakdown.

Get Organization

Return the authenticated Mailfloss organization's plan, credit balances, current-period usage, trial state, account status, and feature entitlements.

Get Usage Report

Return verification usage for a UTC calendar period, optionally scoped to one ESP connection.

List Verification Jobs

Return one page of the organization's verification-job history, newest first, with optional source and lifecycle filters.

Verify Email

Verify one email address and return Mailfloss's raw engine verdict without organization floss-setting overrides.

SETUP GUIDE

Connect mailfloss 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: ["mailfloss"],
  mcp: true,
});
Create a session scoped to mailfloss 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 whether maria@example.com is deliverable using mailfloss.",
  stopWhen: stepCountIs(10),
});

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

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

Run mailfloss tools with your agent

typescript
let response = await client.responses.create({
  model: "gpt-5.6-sol",
  tools,
  input: [{ role: "user", content: "Verify whether maria@example.com is deliverable using mailfloss." }],
});

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 mailfloss tool calls through the session, and print the final answer

Why Use Composio?

AI Native mailfloss Integration

  • Supports both mailfloss MCP and direct API integrations
  • Structured, LLM-friendly schemas for reliable email verification tool execution
  • Access tools for checking addresses and processing asynchronous verification batches

Managed Auth

  • Securely stores your mailfloss API key instead of exposing it in agent prompts
  • Central place to manage, scope, and revoke mailfloss access
  • Per user and per environment credentials for safer API key handling

Agent Optimized Design

  • Tools are tuned using real error and success rates to improve verification reliability over time
  • Clear tool inputs and outputs help agents handle individual checks and asynchronous batch jobs
  • Comprehensive execution logs show what ran, when, and on whose behalf

Enterprise Grade Security

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

Rolling this out across your team?

Give your team centralized access control across every framework with Composio’s MCP Gateway.

EXPLORE MCP GATEWAY
FAQ

Frequently asked questions

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

When you connect a mailfloss account through Composio, every action runs under that account, so anything the agent creates, sends, or changes shows up in mailfloss 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 mailfloss. If mailfloss 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 mailfloss 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 mailfloss 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 mailfloss rejects the old key. Create a new key in mailfloss and reconnect the account from the Composio dashboard or by asking your agent to reconnect mailfloss. Nothing else changes.

Composio's free Hobby plan includes 100,000 tool calls per month with no credit card, which covers most personal mailfloss use. Paid plans add higher limits and team features. Your mailfloss 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 mailfloss accounts).

With Composio, you connect mailfloss 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.

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