Purpose mxprobe is used to provide email address verification for AI agents. A single call returns a disposition for an address, with values of send, hold, or kill, along with a reason. It is suitable for outreach-type agents to determine whether a target address is usable before sending email.
Main capabilities
- Returns two types of results: action is send, hold, or kill; verdict is OK, WEAK, or DEAD.
- Decision rules: in cases of rejection, greylisting, or catch-all, hold does not escalate to kill; kill is returned only when a 5xx response clearly points to that mailbox.
- Verification methods: local DNS checks or hosted SMTP probing.
- Three usage forms: CLI, MCP server, and hosted API.
- Registration and credit purchase can be completed via API, and agents can set it up themselves, with no forms, CAPTCHA, or dashboard required.
How to use
- Site and documentation:https://mxprobe.dev
- API：https://api.mxprobe.dev（在 self-describing at GET /)
- OpenAPI:https://mxprobe.dev/openapi.json
- For agents:https://mxprobe.dev/llms.txt
- npm packages: mxprobe (CLI + MCP server), mxprobe-core (engine)
- One-click installation: Cursor, VS Code, LM Studio. In Claude Code, the same server is also available as a plugin: first run /plugin marketplace add andrewchmr/mxprobe, then run /plugin install mxprobe@mxprobe.
- Tech stack: all TypeScript (strict, ESM). Each package uses tsc -b to compile src/ to dist/; published packages contain only dist/. mxprobe and the server import mxprobe-core's dist/ via workspace links, so you must first run pnpm build in the root directory (running each package in dependency order), then run tests or type checks for an individual package. Tests are .ts files, run directly by Node using built-in type stripping.
- Runtime environment: development and running tests require Node 22.18 or newer (24 recommended); the compiled engine and CLI can run on Node 20, and the server requires Node 22.13 or newer (depends on node:sqlite).
Use cases Suitable for AI outreach agents that need to automatically verify recipient addresses, and for development workflows that want to integrate address verification capabilities via CLI or MCP.
Limitations and billing
- Registration includes 100 free checks, after which it is $9/10,000 checks, one-time payment, credits do not expire.
- Addresses are logged for 24 hours for debugging, then deleted.
- Information on platform support scope, the specific time required for a single check, or metrics such as accuracy is not yet provided.
