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How to connect Neverbounce to Claude

Connect Claude Web, Desktop and Cowork to Neverbounce MCP. Verify a list of emails for bounces, download csv results from last bulk job, and more using natural language, with authentication handled for you.

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NeverBounce is an email verification service that checks the validity of email addresses. It helps businesses improve deliverability and reduce bounce rates.

12 Tools

Introduction

Claude is Anthropic's AI assistant, available on the web, in the desktop app, and on mobile. Cowork is its agent for knowledge work, and it runs on all of those surfaces too. Connected to your apps, Claude can work with your files and services to accomplish complex tasks on your behalf.

This guide walks you through the easiest and most secure way to connect your Neverbounce account to Claude via Composio Connect, enabling it to verify a list of emails for bounces, download CSV results from last bulk job, check your current NeverBounce credit balance, and more such actions on your behalf without compromising your account security.

Setup is the same on Claude Web, Desktop, and Cowork, and you only need to do it once. The connector is tied to your account, so it's available in all three.

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Connecting Neverbounce to Claude Web, Desktop, and Cowork

Two ways to add the Composio connector. Pick whichever you prefer.

1. Add with one click

Click the button. Claude opens with the Composio connector filled in. Click Add, then go to step 2.

Add to Claude

Add manually

In Claude Desktop, click Customize in the left sidebar, then select Connectors and click the + icon at the top.

Claude Desktop connectors screen with Add custom connector selected

Click Add custom connector and paste in the Composio MCP server URL:

bash
https://connect.composio.dev/mcp
Add custom connector dialog with Composio MCP server URL

2. Authorize in your browser

Click Connect. You'll be redirected to a browser window where you can authorize Composio to continue.

Composio authorization screen for Claude Web, Desktop, and Cowork

3. Connect your Neverbounce account

Back in Claude, ask it to connect to Neverbounce or give it any Neverbounce-related task.

For example, ask Claude to:

  • "Verify a list of emails for bounces"
  • "Download CSV results from last bulk job"
  • "Check your current NeverBounce credit balance"

It will prompt you to authenticate and authorize access.

That's it. Composio's tools are now available in Claude, and your Neverbounce account is ready to use.

What is the Neverbounce Claude Connector, and what's possible with it?

The Neverbounce MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Neverbounce account. It provides structured and secure access to your email verification tools, so your agent can perform actions like bulk verifying lists, checking job statuses, downloading results, and managing your account seamlessly.

  • Instant email verification and validation: Quickly verify email addresses for validity to reduce bounce rates and improve deliverability right from your agent.
  • Bulk email job management: Create, start, and track bulk verification jobs for entire email lists, letting your agent handle large-scale email hygiene automatically.
  • Automated job result retrieval: Download or fetch completed job results as CSVs or paginated data, making it easy to integrate verified emails into your workflows.
  • Account usage and credit tracking: Let your agent monitor account stats, credits, and usage so you always know your verification capacity and performance.
  • Secure job and data deletion: Direct your agent to permanently delete outdated or unnecessary jobs, ensuring your data remains clean and compliant.

Troubleshooting

1. Why does Claude not use the Composio connector for Neverbounce?

The connector can show as connected, but Claude must use it in each Neverbounce conversation.

  • Click + at the lower left of the chat, or type /.
  • Hover Connectors.
  • Turn on Composio.
  • Ask Claude to connect to Neverbounce again.

2. Why does Claude show an MCP server error before Neverbounce connects?

Claude can show Couldn't reach the MCP server or Authorization with the MCP server failed when you add the connector for Neverbounce.

  • Check that the connector URL is https://connect.composio.dev/mcp.
  • Connectors run from Anthropic's cloud, so your device network is usually not the problem.
  • Add the connector again from Customize > Connectors, then ask Claude to connect Neverbounce.
  • If it fails again, send the error and the ofid_ reference id to support@composio.dev.

3. Why does the Neverbounce authorization link not work?

The Composio connector is one server. Your Neverbounce account connects separately when Claude asks for it.

  • If the browser does not open, or the link expires, ask Claude to retry the Neverbounce connection.
  • Composio creates a fresh Neverbounce authorization link.
  • Open that link in your browser and finish the Neverbounce sign-in.

4. Why do Neverbounce actions fail after they worked before?

The Neverbounce connection can expire or lose permission.

  • Ask Claude to inspect the Neverbounce connection.
  • If the connection is unhealthy, disconnect it when Claude prompts you.
  • Reconnect the Neverbounce account and retry the action.
  • If Claude shows a permission prompt, approve it before Claude changes data in Neverbounce.
  • If the action still fails with a permission error, check that the connected account has that permission in Neverbounce itself.

5. How do I switch to a different Neverbounce account?

Claude can manage the Neverbounce connection for you.

  • Ask Claude to disconnect or delete the current Neverbounce account.
  • Ask Claude to connect Neverbounce again.
  • Open the new Composio authorization link for Neverbounce.
  • Sign in with the other Neverbounce account in the browser.
  • After the account connects, ask Claude to retry the Neverbounce task.

6. Why is my Neverbounce connection missing in Claude Desktop or on a Team plan?

The connector belongs to your Claude account, so your Neverbounce connection works in Claude Web, Desktop, and Cowork.

  • In Claude Desktop, open Customize > Connectors.
  • Next to Composio, click ⋮ and click Clear cache.
  • If Neverbounce tools still do not appear, click ⋮, disconnect, remove the connector, and add it again.
  • On Team or Enterprise, an Owner or Primary Owner must enable the connector before you can connect Neverbounce.
TOOLS

Supported Tools

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

Get Account Info

Tool to get account information including credits, job counts, and usage statistics.

Confirm Proof of Email

Tool to confirm proof of email ownership (POE) from the JavaScript widget.

Create NeverBounce Bulk Verification Job

Tool to create a new bulk verification job with parsing, sampling, and callback options.

Delete NeverBounce Job

Tool to permanently delete a job and its results.

Download Job Results (GET)

Tool to download job results as a CSV file via GET.

Retrieve Job Results

Tool to retrieve paginated results for a completed job, including original data and verification outcomes.

Start NeverBounce Job

Tool to start a parsed job when auto_start is disabled.

Get bulk job status

Tool to get the status and progress of a bulk verification job.

Parse NeverBounce Job

Tool to parse a job created with auto_parse disabled.

Search bulk verification jobs

Tool to search and list bulk verification jobs in your account with pagination and filtering.

NeverBounce Single Check

Tool to verify a single email address and gather additional information.

JS Widget Send Event

Tool to send widget form events via the JS widget API.

FRAMEWORKS

How to build Neverbounce MCP Agent with another framework

Claude Code logo

Claude Code

Use Neverbounce MCP with Claude Code

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Neverbounce MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

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Codex logo

Codex

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OpenClaw logo

OpenClaw

Use Neverbounce MCP with OpenClaw

Hermes logo

Hermes

Use Neverbounce MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Neverbounce MCP with Atomic Agent

Google ADK logo

Google ADK

Use Neverbounce MCP with Google ADK

LangChain logo

LangChain

Use Neverbounce MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Neverbounce MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Neverbounce MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Neverbounce MCP with LlamaIndex

CrewAI logo

CrewAI

Use Neverbounce MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Neverbounce MCP with Pydantic AI

AutoGen logo

AutoGen

Use Neverbounce MCP with AutoGen

FAQ

Frequently asked questions

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

Yes, you can. Claude Cowork 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 Neverbounce tools.

Yes, absolutely. You can configure which Neverbounce 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 Neverbounce data and credentials are handled as safely as possible.

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