MailProbe

What the MailProbe MCP server does

The MailProbe MCP server lets an AI assistant check whether email addresses are likely to exist and accept mail. Verification examines the address syntax, the domain's mail servers, and the mailbox response without sending an email. Requests are processed in memory, and the API does not retain the address or reuse the result later.

Verification can help with individual lookups, sign-up screening, and list preparation before a campaign. Processing runs on OVHcloud servers in France. The service uses one credit for each address actually probed; malformed entries, duplicates within one request, connection refusals, and certain unresolved results do not consume credits.

How it works

Two deployment paths expose the same tools. The hosted endpoint is available at https://mailprobe.dev/mcp for clients that support remote MCP connections and authorization headers. The local package runs with npx -y mailprobe-mcp, communicates with the client over stdio, and forwards requests to the MailProbe API at https://mailprobe.dev/api/v1.

The API accepts up to 20 addresses in a verification call and returns results in input order. Calls are limited to 60 per minute per API key, with a batch of 20 counting as one call. Responses are designed to complete within about 55 seconds. If an address has not received a verdict by then, it returns unknown with a timeout reason and can be submitted again without a charge. The local process retries eligible rate-limit delays up to two times.

Setup and configuration

Create a MailProbe account, which includes 100 free credits, then create an API key under the Developer section. Keys begin with mp_live_ and are shown only when created.

For the hosted server, place the key in an Authorization: Bearer ... header. For the local server, set MAILPROBE_API_KEY and use Node.js 22 or newer. A client configuration can start the package with npx, passing the key through its environment settings.

Claude Code can install the repository's plugin, which connects to the hosted endpoint and stores the credential in the system credential store. Cursor can connect directly to the hosted endpoint with a header. Claude Desktop uses the local configuration shown by the project. The Claude and ChatGPT apps do not support this service's hosted connection through OAuth; the project notes Zapier MCP as another availability option.

Tools and capabilities

The MailProbe MCP server exposes two tools:

• verify_emails accepts one to 20 addresses and returns valid, invalid, risky, or unknown status, a score from 0 to 100, and a reason when the result is not plainly deliverable.
• Each verification result also includes disposable, role_based, free_provider, and catch_all flags, plus did_you_mean when a likely typo is detected.
• get_credits reports the credits remaining for the API key and is free to call.

Lists larger than 20 addresses must be split across calls. For a few hundred or more addresses, MailProbe's account batch screen supports pasted lists up to 500 addresses and CSV or TXT files up to 250,000 addresses, with background processing.

Limitations and notes

The server does not send messages, but its result is a verification verdict rather than a guarantee that delivery will succeed. A catch_all domain or an unknown result may require additional review. Rate-limit refusals include a wait duration, and other errors explain the required action, such as setting a key or adding credits.

Without a key, the local process can start and list its tools, but a tool call explains how to configure MAILPROBE_API_KEY. The local server adds a versioned User-Agent value to requests, which can help support identify its API traffic.