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How to connect Zerobounce to Claude

Connect Claude Web, Desktop and Cowork to Zerobounce MCP. Validate a list of 100 new signups, score this email for lead quality, and more using natural language, with authentication handled for you.

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ZeroBounce is an email validation and deliverability platform that detects invalid or risky email addresses. It helps businesses improve email marketing results by ensuring emails actually reach real people.

20 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 Zerobounce account to Claude via Composio Connect, enabling it to validate a list of 100 new signups, score this email for lead quality, check deliverability of mark@gmail.com, 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.

Also integrate Zerobounce with

Claude CodeOpenAI Agents SDKClaude Agent SDKCodexOpenClawHermesAtomic AgentGoogle ADKLangChainVercel AI SDKMastra AILlamaIndexCrewAIPydantic AIAutoGen

Connecting Zerobounce 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 Zerobounce account

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

For example, ask Claude to:

  • "Validate a list of 100 new signups"
  • "Score this email for lead quality"
  • "Check deliverability of mark@gmail.com"

It will prompt you to authenticate and authorize access.

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

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

The Zerobounce MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Zerobounce account. It provides structured and secure access to your email validation and deliverability tools, so your agent can perform actions like validating emails, scoring leads, managing bulk jobs, and analyzing engagement—all automatically.

  • Real-time email validation: Instantly check if email addresses are valid, risky, or undeliverable before sending campaigns or updating your lists.
  • Bulk validation and processing: Upload files and process hundreds of emails or domains at once, with tools for tracking job status and retrieving results.
  • AI-powered lead scoring: Score individual email addresses using Zerobounce AI to assess lead quality and prioritize outreach.
  • Domain and pattern analysis: Identify common email address formats for any domain or run bulk domain searches to optimize your contact strategies.
  • Allowlist and blocklist management: Easily update your allow and block lists to fine-tune which addresses pass or fail validation, keeping your lists clean and secure.

Troubleshooting

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

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

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

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

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

  • 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 Zerobounce.
  • If it fails again, send the error and the ofid_ reference id to support@composio.dev.

3. Why does the Zerobounce authorization link not work?

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

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

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

The Zerobounce connection can expire or lose permission.

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

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

Claude can manage the Zerobounce connection for you.

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

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

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

  • In Claude Desktop, open Customize > Connectors.
  • Next to Composio, click ⋮ and click Clear cache.
  • If Zerobounce 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 Zerobounce.
TOOLS

Supported Tools

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

Get Activity Data

Tool to get activity data (opens, clicks, etc.

AI Scoring Single Email

Tool to score a single email address using ZeroBounce AI.

Allow or Block List

Tool to manage allowlist and blocklist for email validation.

Batch Validate Emails

Tool to validate a batch of email addresses in real time.

Delete AI Scoring File

Tool to remove a completed AI scoring file from ZeroBounce servers.

Delete file

Tool to delete a file that was submitted for bulk validation.

Domain Search File Status

Tool to get the processing status of a file submitted for bulk domain search.

Domain Search Get File

Tool to download the results file for a completed bulk domain search job.

Domain Search Send File

Tool to upload a file for bulk domain search.

Domain Search Single

Tool to identify common email address formats for a given domain.

Delete Email Finder File

Tool to delete a file that was submitted for bulk email finding.

Email Finder File Status

Tool to get the processing status of a file submitted for bulk email finding.

Email Finder Send File

Tool to upload a file for bulk email finding.

Get API Usage

Tool to retrieve API usage statistics for a given period.

Get Credit Balance

Tool to retrieve your current ZeroBounce email validation credit balance.

Get Email Finder File

Tool to download the results file for a completed bulk email finder job.

List Evaluator

Tool to evaluate the quality of an email list.

List Filters

Tool to retrieve all email addresses and domains in your allowlist and blocklist filters.

Send File

Tool to upload a file for bulk email validation.

Validate Email

Tool to validate a single email address in real time.

FRAMEWORKS

How to build Zerobounce MCP Agent with another framework

Claude Code logo

Claude Code

Use Zerobounce MCP with Claude Code

OpenAI Agents SDK logo

OpenAI Agents SDK

Use Zerobounce MCP with OpenAI Agents SDK

Claude Agent SDK logo

Claude Agent SDK

Use Zerobounce MCP with Claude Agent SDK

Codex logo

Codex

Use Zerobounce MCP with Codex

OpenClaw logo

OpenClaw

Use Zerobounce MCP with OpenClaw

Hermes logo

Hermes

Use Zerobounce MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Zerobounce MCP with Atomic Agent

Google ADK logo

Google ADK

Use Zerobounce MCP with Google ADK

LangChain logo

LangChain

Use Zerobounce MCP with LangChain

Vercel AI SDK logo

Vercel AI SDK

Use Zerobounce MCP with Vercel AI SDK

Mastra AI logo

Mastra AI

Use Zerobounce MCP with Mastra AI

LlamaIndex logo

LlamaIndex

Use Zerobounce MCP with LlamaIndex

CrewAI logo

CrewAI

Use Zerobounce MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Zerobounce MCP with Pydantic AI

AutoGen logo

AutoGen

Use Zerobounce MCP with AutoGen

FAQ

Frequently asked questions

With a standalone Zerobounce MCP server, the agents and LLMs can only access a fixed set of Zerobounce tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Zerobounce 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 Zerobounce tools.

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

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