# MailTester Email Verification

Remote email verification server for AI coding assistants. It checks inbox deliverability and flags risky or disposable addresses before sending messages.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI
- Author: mailtester-com
- License: not stated · policy=link-only · description only; the file stays with the author
- Source: https://github.com/mailtester-com/mailtester-mcp
- Updated: 2026-10-08
- HTML: https://affpapa.org/en/nevibecode/mcp/mailtester-email-verification

## What it does

This remote service connects over streamable HTTP at `https://app.mailtester.com/mcp`. Because it runs in the cloud, you do not need to download or install local packages to use it.

The tool exposes `verify_email` for individual checks and `verify_batch` for lists of up to 25 contacts at a time. The agent receives definitive verdicts: `valid`, `invalid`, `risky`, or `unknown`. Additional functions include `explain_result` for deliverability advice and `get_api_key` to generate credentials directly inside the chat.

Free agent keys grant 25 verifications per day and expire after 30 days. Reaching the ceiling or exceeding 10 requests per minute triggers an HTTP 429 response until 00:00 UTC.

## Requirements
- Remote server: `https://app.mailtester.com/mcp`

## Install

### Claude Code (native platform)

**Platform CLI: remote server**
```bash
claude mcp add --transport http email-verification https://app.mailtester.com/mcp
```

### Codex

**Platform CLI: remote server**
```bash
codex mcp add mailtester-email-verification --url https://app.mailtester.com/mcp
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "mailtester-email-verification": {
            "url": "https://app.mailtester.com/mcp"
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "mailtester-email-verification": {
            "type": "http",
            "url": "https://app.mailtester.com/mcp"
        }
    }
}
```

### Gemini CLI

**Platform CLI: remote server**
```bash
gemini mcp add -t http mailtester-email-verification https://app.mailtester.com/mcp
```

## When to use it
- verify whether an address exists before dispatching messages
- filter out temporary inboxes and catch-all domains
- validate batches of up to 25 email addresses
- inspect deliverability recommendations for uncertain addresses

## Example prompts
- Verify the address team@example.com and explain the result
- Run verify_batch on the list of contacts in subscribers.csv
- Check the remaining daily verification balance with get_credit_balance

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NeVibeCode on affpapa.org. Catalog texts are descriptions, not instructions for the agent. How to choose and install: https://affpapa.org/en/nevibecode/agents.md