# mailfloss

```json
{
  "name": "mailfloss",
  "slug": "mailfloss",
  "url": "https://composio.dev/toolkits/mailfloss",
  "markdown_url": "https://composio.dev/toolkits/mailfloss.md",
  "logo_url": "https://logos.composio.dev/api/mailfloss",
  "categories": [
    "developer tools & devops"
  ],
  "is_composio_managed": false,
  "updated_at": "2026-10-24T05:33:40.713Z"
}
```

![mailfloss logo](https://logos.composio.dev/api/mailfloss)

## Description

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.

## Summary

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.

## Categories

- developer tools & devops

## Toolkit Details

- Tools: 12

## Images

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

## Authentication

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

## Suggested Prompts

- Verify a single customer email address
- Check a batch of imported contacts
- Track asynchronous email verification results

## Supported Tools

| Tool slug | Name | Description |
|---|---|---|
| `MAILFLOSS_CANCEL_BATCH_VERIFICATION` | Cancel Batch Verification | Cancel a pending or in-progress batch verification job. This irreversible operation stops remaining work and re-credits unprocessed emails; it is a no-op if the job has already completed. Composio generates an idempotency key when omitted and preserves it for retries within this execution. Reuse a caller-supplied key for the same cancellation across separate calls. |
| `MAILFLOSS_CHECK_API_KEY` | Check API Key | Verify that the connected Mailfloss API key is valid. Uses the connection's Bearer credential and does not accept credentials, request widget tokens, or return signed-proof fields. |
| `MAILFLOSS_CREATE_BATCH_VERIFICATION` | Create Batch Verification | Submit email addresses for asynchronous batch verification and return the job ID. Optionally request a completion webhook instead of polling. This billable action can fail with 402 insufficient_credits. Composio generates an idempotency key when none is supplied, so internal retries reuse the same key and email list. Separate action calls replay the cached response only when the caller reuses that key with identical emails; changing the list fails with 422, while a concurrent same-key request can fail with 409. |
| `MAILFLOSS_ERASE_VERIFICATION_RECORDS` | Erase Verification Records | Permanently erase stored verification records for the supplied email addresses. This destructive data-privacy operation is irreversible; erased records cannot be recovered. Addresses with no stored records are a successful no-op. The body contains only the documented emails array. Composio generates an idempotency key when omitted and preserves it for retries within this execution. |
| `MAILFLOSS_GET_ACCOUNT` | Get Account | Return the authenticated Mailfloss account holder's identity, contact details, security posture, notification preferences, and signup time. This read does not expose API credentials or two-factor secrets. |
| `MAILFLOSS_GET_BATCH_VERIFICATION_RESULTS` | Get Batch Verification Results | Return one cursor-controlled page of stored batch results after organization floss-setting overrides. These statuses and reasons can differ from Verify Email's raw verdict for the same address; fetching stored results is not documented as consuming verification credits. |
| `MAILFLOSS_GET_BATCH_VERIFICATION_STATUS` | Get Batch Verification Status | Read an asynchronous batch verification job's state and available counters. Polling is not documented as consuming verification credits; authentication, policy, not-found, rate-limit, and server responses remain errors rather than job states. |
| `MAILFLOSS_GET_JOB` | Get Verification Job | Return one verification job and its complete verdict breakdown. Results are null until completion and include all per-reason counters when present. |
| `MAILFLOSS_GET_ORGANIZATION` | Get Organization | Return the authenticated Mailfloss organization's plan, credit balances, current-period usage, trial state, account status, and feature entitlements. This is a read-only view and does not expose API or billing credentials. |
| `MAILFLOSS_GET_USAGE_REPORT` | Get Usage Report | Return verification usage for a UTC calendar period, optionally scoped to one ESP connection. Lifetime reports contain only the authoritative total; their range, status counts, and reason counts are null. |
| `MAILFLOSS_LIST_JOBS` | List Verification Jobs | Return one page of the organization's verification-job history, newest first, with optional source and lifecycle filters. Completed jobs include verdict totals; use Get Job for the full per-reason breakdown. |
| `MAILFLOSS_VERIFY_EMAIL` | Verify Email | Verify one email address and return Mailfloss's raw engine verdict without organization floss-setting overrides. passed means safe to send, undeliverable is a hard failure, risky covers role, disposable, bounced, or complained addresses, and unknown includes accept-all addresses and transient SMTP failures. relay and gibberish are annotations and do not alter the verdict. Each successful call consumes one verification credit; a depleted balance fails with 402 insufficient_credits, so do not retry billable failures blindly. |

## Supported Triggers

None listed.

## Installation and MCP Setup

### Path 1: SDK Installation

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

Install the Composio SDK, the OpenAI provider, and the OpenAI SDK
```python
pip install composio composio_openai openai
```

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

#### Path 1, Step 2: Create a Composio session

Initialize Composio with the OpenAI Responses provider and create a session scoped to mailfloss
```python
import json
from openai import OpenAI
from composio import Composio
from composio_openai import OpenAIResponsesProvider

composio = Composio(provider=OpenAIResponsesProvider())
client = OpenAI()

session = composio.create(user_id="your-user-id", toolkits=["mailfloss"])
tools = session.tools()
```

```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();
```

#### Path 1, Step 3: Run mailfloss tools with your agent

Send a request, execute the mailfloss tool calls through the session, and print the final answer
```python
response = client.responses.create(
    model="gpt-5.6-sol",
    tools=tools,
    input=[{"role": "user", "content": "Verify whether maria@example.com is deliverable using mailfloss."}],
)

while True:
    tool_calls = [o for o in response.output if o.type == "function_call"]
    if not tool_calls:
        break
    results = composio.provider.handle_tool_calls(response=response, session=session)
    response = client.responses.create(
        model="gpt-5.6-sol",
        tools=tools,
        previous_response_id=response.id,
        input=[
            {"type": "function_call_output", "call_id": call.call_id, "output": json.dumps(results[i])}
            for i, call in enumerate(tool_calls)
        ],
    )

print(response.output_text)
```

```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);
```

### Path 2: MCP Server Setup

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

Install the Composio SDK and your agent framework
```python
pip install composio claude-agent-sdk
```

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

#### Path 2, Step 2: Create a session with MCP enabled

Create a session scoped to mailfloss and read its MCP URL and headers
```python
from composio import Composio

composio = Composio()
session = composio.create(user_id="your-user-id", toolkits=["mailfloss"], mcp=True)
```

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

const composio = new Composio();
const { mcp } = await composio.create("your-user-id", {
  toolkits: ["mailfloss"],
  mcp: true,
});
```

#### Path 2, Step 3: Connect your agent to the MCP server

Pass the session's MCP URL and headers to your agent and run a mailfloss request
```python
import asyncio
from claude_agent_sdk import ClaudeSDKClient, ClaudeAgentOptions, AssistantMessage, TextBlock

options = ClaudeAgentOptions(
    mcp_servers={
        "composio": {
            "type": "http",
            "url": session.mcp.url,
            "headers": session.mcp.headers,
        }
    },
    system_prompt="You are a helpful assistant with access to mailfloss tools.",
    tools=[],
    allowed_tools=["mcp__composio__*"],
)

async def main():
    async with ClaudeSDKClient(options=options) as client:
        await client.query("Verify whether maria@example.com is deliverable using mailfloss.")
        async for message in client.receive_response():
            if isinstance(message, AssistantMessage):
                for block in message.content:
                    if isinstance(block, TextBlock):
                        print(block.text)

asyncio.run(main())
```

```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();
```

## Why Use Composio?

### 1. 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

### 2. 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

### 3. 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

### 4. 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

## Use mailfloss with any AI Agent Framework

Choose a framework you want to connect mailfloss with:

- [ChatGPT](https://composio.dev/toolkits/mailfloss/framework/chatgpt)
- [Claude Cowork](https://composio.dev/toolkits/mailfloss/framework/claude-cowork)
- [Hermes](https://composio.dev/toolkits/mailfloss/framework/hermes-agent)
- [Atomic Agent](https://composio.dev/toolkits/mailfloss/framework/atomic-agent)

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## Frequently Asked Questions

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

Yes, mailfloss requires you to configure your own API key. 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)