MX Probe

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

Quick Install

Automated & IDE Setup

Copy the AI prompt to install this server into Claude Code, Cursor, or another agent — or use 1-click editor setup below.

One-click editor setup isn’t available for this listing yet — we don’t have a confirmed install command, and we’d rather show nothing than point your editor at the wrong package or host. Follow the project’s own setup instructions, linked above.

Manual Client & Custom JSON ConfigExpand JSON ▾

No confirmed setup config for this listing yet. We only publish a config block when the install details come from the project itself — its README, its docs, or a verified owner. We haven’t found those for MX Probe, and we’d rather show nothing than a guess you’d paste into your client. Follow the project’s own setup instructions for the current steps.

Documentation Overview

MX Probe

Email verification for AI agents. One call returns send, hold or kill for an address, with the reason. Signup and credits happen by API too, so an outreach agent can provision itself. No form, no CAPTCHA, no dashboard.

Site and docs: https://mxprobe.dev
API: https://api.mxprobe.dev (it describes itself on GET /). OpenAPI: https://mxprobe.dev/openapi.json. For agents: https://mxprobe.dev/llms.txt
npm: mxprobe (CLI + MCP server), mxprobe-core (the engine)

Terminal

npx mxprobe check hello@example.com          # free DNS tier, local, no key
npx mxprobe check --hosted hello@example.com # survivors go to the hosted SMTP probe
claude mcp add mxprobe -- npx -y mxprobe mcp # the MCP server

One click: Cursor · VS Code · LM Studio. In Claude Code the same server also comes as a plugin: /plugin marketplace add andrewchmr/mxprobe, then /plugin install mxprobe@mxprobe.

config.json

{
  "email": "hello@example.com",
  "action": "send",
  "verdict": "OK",
  "reason": "mailbox accepted by aspmx.l.google.com",
  "checks": { "syntax": true, "mx": "aspmx.l.google.com", "smtp": "accepted", "catch_all": false }
}

action is send, hold or kill; verdict is OK, WEAK or DEAD. A hold never becomes a kill on a refusal, a greylist or a catch-all. Only a 5xx that names the mailbox kills.

Layout

Path	What
`packages/core`	The engine: DNS tier, SMTP probe, the verdict contract and the API's wire types. Zero dependencies.
`packages/cli`	`npx mxprobe check
`server`	The hosted API: `node:http` + `node:sqlite`, Stripe Checkout, Resend, Telegram.
`site`	The landing page, static.
`deploy`	Caddyfile, systemd units, the install script and the runbook.

Develop

Everything is TypeScript (strict, ESM). Each package compiles its src/ to dist/ with tsc -b; the published packages ship dist/ only. mxprobe and the server import mxprobe-core through the workspace link to its dist/, so pnpm build at the root (which runs the packages in dependency order) must come before a single package's test or typecheck. Tests are .ts files that Node runs directly with its built-in type stripping.

bash

pnpm install
pnpm build                      # tsc -b in each package, core first
pnpm test                       # builds, then: fake resolver, fake SMTP server, in-memory SQLite. No network.
pnpm typecheck                  # the sources and the tests, without emitting
pnpm test:live                  # the DNS tier against the real network
pnpm check a@b.com              # the CLI from this checkout
cp server/.env.example server/.env && pnpm dev:server

Node 22.18 or newer (24 recommended) to develop and to run the tests; the compiled engine and CLI run on Node 20, the server on 22.13 or newer (node:sqlite).

Pricing

100 checks free at signup, then 9 USD per 10,000, one payment, credits never expire. Addresses are logged for 24 hours for debugging and then deleted.

MIT.

Read the full README →View source on GitHub →

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Frequently Asked Questions about MX Probe

We don't have a confirmed install command for MX Probe yet, so we don't publish a generated one — a guessed package name would point at the wrong package or none at all. Follow the project's own README or setup instructions (https://github.com/andrewchmr/mxprobe) for the current steps.

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Technical Specs & Signals

CategoryCommunication

27Quality signal: Emerging · 27/100How this signal is calculated ▾

Server availabilityNot measured

Not scored for repo-hosted servers — we can't reach the running server, only its GitHub page. Hosted MCP endpoints are health-checked live.

Verified ownership8/20

Documentation & tools11/30

Adoption & activity1/15

Community engagement0/10

A guidance signal from public completeness & health data — not a user rating. New listings start lower and rise as they add docs, get verified, and grow adoption. Signals we can't observe for a listing are skipped, not counted against it.

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More in 💬 Communication →Best MCP servers for Slack & Communication →Alternatives to MX Probe →Install in Claude Desktop Install in Cursor Install in VS Code Setup guides for all 13 MCP clients

Documentation Overview

MX Probe

Site and docs: https://mxprobe.dev
API: https://api.mxprobe.dev (it describes itself on GET /). OpenAPI: https://mxprobe.dev/openapi.json. For agents: https://mxprobe.dev/llms.txt
npm: mxprobe (CLI + MCP server), mxprobe-core (the engine)

Terminal

npx mxprobe check hello@example.com          # free DNS tier, local, no key
npx mxprobe check --hosted hello@example.com # survivors go to the hosted SMTP probe
claude mcp add mxprobe -- npx -y mxprobe mcp # the MCP server

One click: Cursor · VS Code · LM Studio. In Claude Code the same server also comes as a plugin: /plugin marketplace add andrewchmr/mxprobe, then /plugin install mxprobe@mxprobe.

config.json

{
  "email": "hello@example.com",
  "action": "send",
  "verdict": "OK",
  "reason": "mailbox accepted by aspmx.l.google.com",
  "checks": { "syntax": true, "mx": "aspmx.l.google.com", "smtp": "accepted", "catch_all": false }
}

action is send, hold or kill; verdict is OK, WEAK or DEAD. A hold never becomes a kill on a refusal, a greylist or a catch-all. Only a 5xx that names the mailbox kills.

Layout

Path	What
`packages/core`	The engine: DNS tier, SMTP probe, the verdict contract and the API's wire types. Zero dependencies.
`packages/cli`	`npx mxprobe check
`server`	The hosted API: `node:http` + `node:sqlite`, Stripe Checkout, Resend, Telegram.
`site`	The landing page, static.
`deploy`	Caddyfile, systemd units, the install script and the runbook.

Develop

bash

pnpm install
pnpm build                      # tsc -b in each package, core first
pnpm test                       # builds, then: fake resolver, fake SMTP server, in-memory SQLite. No network.
pnpm typecheck                  # the sources and the tests, without emitting
pnpm test:live                  # the DNS tier against the real network
pnpm check a@b.com              # the CLI from this checkout
cp server/.env.example server/.env && pnpm dev:server

Node 22.18 or newer (24 recommended) to develop and to run the tests; the compiled engine and CLI run on Node 20, the server on 22.13 or newer (node:sqlite).

Pricing

100 checks free at signup, then 9 USD per 10,000, one payment, credits never expire. Addresses are logged for 24 hours for debugging and then deleted.

MIT.

Frequently Asked Questions about MX Probe