# MX Probe (npm · mxprobe)

Email verification for AI agents: send, hold or kill with the reason. Signup and credits by API.

- Trust score: 84/100 (high trust)
- Change this week: +18
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-09-20

## Components

- npm · `mxprobe`: 84/100 (this document), [markdown](https://verifymcp.io/servers/dev-mxprobe-mxprobe/mxprobe.md), [page](https://verifymcp.io/servers/dev-mxprobe-mxprobe/mxprobe)

## Channel facts

- Registry: `npm`
- Package: `mxprobe`
- Version: `0.2.5`
- Transport: `stdio`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically from public evidence about the published package, including repeated runs of it in an isolated sandbox, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-09-20.

- **Supply Chain Security**: 98/100
  - No malware found by supply-chain analysis.
  - No known CVEs affecting this package version or its production dependencies.
  - No install/post-install scripts declared.
  - 31 of 96 dependencies flagged as unhealthy.
- **Provenance & Transparency**: 97/100
  - Source repository is publicly reachable at the declared URL.
  - Cryptographically verified build provenance (signed, bound to andrewchmr/mxprobe).
  - Clear OSI-approved license (MIT).
  - Actively maintained (last published 4 days ago).
  - Disclosure check failed: no security disclosure policy was found in the source repository.
- **Schema Quality & AI Usability**: 78/100
  - AI-judged instruction clarity (excellent).
  - Tool/resource definitions use about 472 tokens (~94/item across 5 items; 5 tools + 0 resources), lean.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 23/100
  - Stability observed for 7 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 5 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 5 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### How do I install the MX Probe MCP server?

MX Probe runs locally as an npm package, launched with npx -y mxprobe. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add dev-mxprobe-mxprobe -- npx -y mxprobe
```

### Cursor

```json
{
  "mcpServers": {
    "dev-mxprobe-mxprobe": {
      "command": "npx",
      "args": [
        "-y",
        "mxprobe"
      ]
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "dev-mxprobe-mxprobe": {
      "command": "npx",
      "args": [
        "-y",
        "mxprobe"
      ]
    }
  }
}
```

### Codex

```bash
codex mcp add dev-mxprobe-mxprobe -- npx -y mxprobe
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "dev-mxprobe-mxprobe": {
      "type": "local",
      "command": [
        "npx",
        "-y",
        "mxprobe"
      ],
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add dev-mxprobe-mxprobe --command npx --arg -y --arg mxprobe
```

### Hermes

```yaml
mcp_servers:
  dev-mxprobe-mxprobe:
    command: "npx"
    args: ["-y", "mxprobe"]
```

### Netclaw

```json
{
  "McpServers": {
    "dev-mxprobe-mxprobe": {
      "Transport": "stdio",
      "Command": "npx",
      "Arguments": [
        "-y",
        "mxprobe"
      ]
    }
  }
}
```

### Vellum

```bash
assistant mcp add dev-mxprobe-mxprobe -t stdio -c npx -a -y mxprobe
```

### Other

```json
{
  "mcpServers": {
    "dev-mxprobe-mxprobe": {
      "command": "npx",
      "args": [
        "-y",
        "mxprobe"
      ]
    }
  }
}
```

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-09-19 (score 84, +1)

No change was recorded against any check on this day. Stability & Change Management went from 17 to 20. That category is still filling its 30-day observation window: 5 days of observed history at the previous scan, 6 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-17 (score 83, +1)

No change was recorded against any check on this day. Stability & Change Management went from 10 to 13. That category is still filling its 30-day observation window: 3 days of observed history at the previous scan, 4 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-09-16 (score 82, +15)

- [security improvement] Malware scan: unverified → pass

### 2026-09-15 (score 67, −14)

- [security regression] Malware scan: pass → unverified
- [functional improvement] Stability: unverified → 0.07
- [functional] Package version: 0.2.4 → 0.2.5

### 2026-09-14 (score 81, +15)

- [security improvement] Malware scan: unverified → pass

### 2026-09-13 (score 66)

First indexed and scored.

## MCP tools (5)

### `verify_email` (~165 tokens)

Verify one email address

Check whether an email address can receive mail before sending to it. Each result is { email, action, verdict, reason, checks }. action is send | hold | kill: send means go ahead, hold means send only with a fallback in hand (catch-all, forwarder, greylisted or refused probe), kill means never send (no mail server, or the mailbox does not exist). checks.smtp is skipped on the free DNS tier; the hosted tier probes the mailbox. Uses the hosted SMTP probe (1 credit) when an API key is configured and hosted is not false; otherwise the free local DNS tier.

Input parameters:

- `email` (string, required): The address to check
- `hosted` (boolean): Probe the mailbox on the hosted tier (default: yes when a key is configured)

### `verify_batch` (~155 tokens)

Verify a list of email addresses

Check up to 500 addresses in one call. Each result is { email, action, verdict, reason, checks }. action is send | hold | kill: send means go ahead, hold means send only with a fallback in hand (catch-all, forwarder, greylisted or refused probe), kill means never send (no mail server, or the mailbox does not exist). checks.smtp is skipped on the free DNS tier; the hosted tier probes the mailbox. DNS kills cost nothing; with a key the survivors go to the hosted probe at 1 credit each.

Input parameters:

- `emails` (array, required): The addresses to check
- `hosted` (boolean): Probe mailboxes on the hosted tier (default: yes when a key is configured)

### `signup` (~64 tokens)

Create an MX Probe API key

Sign up with an email address. Returns an API key with 100 free checks and saves it locally for the other tools. The key is also mailed to the address. One key per address.

Input parameters:

- `email` (string, required): The operator's email address, where the key is mailed

### `balance` (~19 tokens)

Credits left

How many hosted checks are left on the configured API key.

### `buy_credits` (~69 tokens)

Buy credits

Get a Stripe Checkout link for more hosted checks: 9 USD per 10,000, one payment, credits never expire. Open the link to pay; credits land on the key when Stripe confirms.

Input parameters:

- `packs` (integer): How many packs of 10,000 (default 1)

## Diagnostics

Captured diagnostic sections: Provenance, Dependencies. The full working is on the page: https://verifymcp.io/servers/dev-mxprobe-mxprobe/mxprobe#diagnostics

## Score history

- 2026-09-20: 84
- 2026-09-19: 84
- 2026-09-18: 83
- 2026-09-17: 83
- 2026-09-16: 82
- 2026-09-15: 67
- 2026-09-14: 81
- 2026-09-13: 66

## Common questions

### What is the MX Probe MCP server?

MX Probe is an MCP server listed in the public MCP registry as dev.mxprobe/mxprobe. Email verification for AI agents: send, hold or kill with the reason. Signup and credits by API. This page covers its npm package (mxprobe).

### Is the MX Probe MCP server safe to use?

MX Probe scores 84 out of 100 on VerifyMCP. We found no known CVEs affecting it as of 20 September 2026. It declares no install or post-install scripts. Its build provenance is signed and verified. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the MX Probe MCP server expose?

MX Probe exposes 5 tools: verify_email, verify_batch, signup, balance, buy_credits. Their descriptions and schemas cost roughly 472 tokens of context every time the server is loaded.

### Is the MX Probe MCP server still maintained?

MX Probe is still listed as active in the MCP registry. We last reached this channel on 20 September 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What licence is the MX Probe MCP server under?

MX Probe declares the MIT licence, which is OSI-approved. That covers the source only, and says nothing about the cost of any service it calls.

## Links

- npm package: https://www.npmjs.com/package/mxprobe
- Socket report: https://socket.dev/npm/package/mxprobe
- Repository: https://github.com/andrewchmr/mxprobe
- Website: https://mxprobe.dev/
- Changelog RSS feed: https://verifymcp.io/servers/dev-mxprobe-mxprobe/mxprobe.xml
- Changelog JSON feed: https://verifymcp.io/servers/dev-mxprobe-mxprobe/mxprobe.json
- HTML version of this page: https://verifymcp.io/servers/dev-mxprobe-mxprobe/mxprobe