Check if an e-mail address has an Outlook account

The Outlook check answers whether an e-mail address has an account on Microsoft's consumer mail service. That covers outlook.com and the older hotmail.com, live.com and msn.com addresses. It runs in bulk jobs and returns registered: true, false or null (unknown) for each address, with the time we checked. Nothing is sent to the address and no mailbox is read.

#What does the Outlook check tell you?

It tells you whether Microsoft has a consumer mailbox at the address. Outlook.com is where Microsoft's free web mail lives today. Microsoft launched it in 2012 and moved Hotmail users onto it in 2013, keeping their addresses. As a result, a single list often mixes @outlook.com, @hotmail.com, @hotmail.co.uk, @live.com and @msn.com, all served by the same system.

• registered: true: an account exists at this address.
• registered: false: a conclusive "no account".
• registered: null: no conclusive answer, with status and reason explaining why. You are not charged.

Old Hotmail and Live addresses make this check useful. Some of them are still active after twenty years, and many were abandoned long ago. The check tells the two apart without sending anything. Work and school mailboxes on Microsoft 365 use the organisation's own domain and are managed by that organisation. They are not consumer Outlook.com accounts.

#Who uses it, and why?

Outlook-family domains are common in older customer databases, which makes them a typical source of bounces and stale records.

• Re-activating old customer data. Before a legitimate transactional or service mailing to customers you already have, a batch run shows which hotmail.com and live.com addresses no longer have an account.
• Deliverability. Large mailbox providers watch bounce rates. Removing addresses that no longer exist protects the reputation that your receipts and password resets depend on.
• Sign-up checks after the fact. A periodic job over new registrations flags Outlook addresses that never existed. That is typical of throwaway sign-ups. See OTP and sign-up fraud.

For an answer while the user is still on the form, use the real-time mailbox check. For phone numbers linked to a Microsoft account, see the Microsoft account number check.

#What do you get back?

Each address is a row with kind: "email" and one entry per requested check in checks.

Downloads add the columns outlook.email.status, outlook.email.registered and outlook.email.billed. Inputs are masked in stored results.

#How is it billed?

You pay the bulk price per address with a conclusive answer. You're not charged for inconclusive results (unknown, unsupported country, timeout, invalid, duplicate). The free POST /v1/jobs/estimate call counts valid, invalid, duplicate and cached rows and returns the maximum cost before you commit. See pricing for current rates.

Repeat checks of the same address inside the freshness window can come from your account's cache, and cache hits are free. If you cancel a running job, rows that have not started are released and not billed.

#What are the limits?

The Outlook check is bulk only. POST /v1/lookup answers 403 service_disabled with "The check 'outlook.email' is available in bulk jobs only (POST /v1/jobs)." A job accepts up to 50,000 numbers and e-mails, as JSON emails or as a CSV upload with an email column.

• Up to 20 checks per request. Identifiers × applicable checks may not exceed 100,000 per job.
• Requests that look like sequential number ranges or generated e-mail lists are rejected. Twenty or more addresses in one request on one domain whose local parts differ only by digits or separators are refused with suspected_enumeration. Live keys are also limited to 50 addresses of one such pattern per account per UTC day.
• Addresses are only trimmed and lowercased, never rewritten.
• The daily cap counts e-mail addresses like numbers (see GET /v1/limits).

#How do I use it responsibly?

Check addresses that belong to your own customers, users or leads. We never open mailboxes and never send e-mail to the address. The answer is yes, no or unknown, and never a name, avatar or profile.

A "yes" does not mean the person agreed to hear from you. Don't use the check to build or "clean" lists for unsolicited e-mail. The acceptable use policy forbids that, along with guessing addresses. Anyone can object through the opt-out form. Suppressed addresses are skipped and free.

#Example request

With a test key, test.mobilevalidate.com addresses give fixed answers (see test mode).

curl https://api.mobilevalidate.com/v1/jobs \
  -H "Authorization: Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym" \
  -H "Content-Type: application/json" \
  -d '{"emails":["[email protected]","[email protected]","[email protected]"],"checks":["outlook"]}'

// npm install mobilevalidate · Node.js 20+ · save as check.mjs and run: node check.mjs
import { MobileValidate } from "mobilevalidate";

// Omit apiKey to read MOBILEVALIDATE_API_KEY from the environment.
const mv = new MobileValidate({ apiKey: "mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym" });
const { data, error } = await mv.jobs.create({
  emails: [
    "[email protected]",
    "[email protected]",
    "[email protected]",
  ],
  checks: ["outlook"],
});
if (error) console.error(error.code, error.message);
else console.dir(data, { depth: null });

// Node.js 18+, Deno, Bun or the browser console (ES module: save as .mjs or use "type": "module").
const res = await fetch("https://api.mobilevalidate.com/v1/jobs", {
  method: "POST",
  headers: {
    Authorization: "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    emails: [
      "[email protected]",
      "[email protected]",
      "[email protected]",
    ],
    checks: ["outlook"],
  }),
});
console.log(res.status, res.headers.get("x-request-id"));
console.dir(await res.json(), { depth: null });

# pip install mobilevalidate-sdk
from mobilevalidate import MobileValidate

# Omit api_key to read MOBILEVALIDATE_API_KEY from the environment.
mv = MobileValidate(api_key="mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym")
result = mv.jobs.create(
    emails=[
        "[email protected]",
        "[email protected]",
        "[email protected]",
    ],
    checks=["outlook"],
)
print(result)

<?php
$ch = curl_init('https://api.mobilevalidate.com/v1/jobs');
curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'Authorization: Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => json_encode([
        'emails' => [
            '[email protected]',
            '[email protected]',
            '[email protected]',
        ],
        'checks' => ['outlook'],
    ]),
]);
$response = curl_exec($ch);
echo curl_getinfo($ch, CURLINFO_RESPONSE_CODE), PHP_EOL, $response, PHP_EOL;

package main

import (
	"fmt"
	"io"
	"net/http"
	"strings"
)

func main() {
	body := strings.NewReader(`{"emails":["[email protected]","[email protected]","[email protected]"],"checks":["outlook"]}`)
	req, err := http.NewRequest("POST", "https://api.mobilevalidate.com/v1/jobs", body)
	if err != nil {
		panic(err)
	}
	req.Header.Set("Authorization", "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym")
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}

require "net/http"
require "json"

uri = URI("https://api.mobilevalidate.com/v1/jobs")
req = Net::HTTP::Post.new(uri)
req["Authorization"] = "Bearer mv_test_publicSandboxn9ZgneuhR1B9CRfKG3fulym"
req["Content-Type"] = "application/json"
req.body = JSON.generate({
  "emails" => [
    "[email protected]",
    "[email protected]",
    "[email protected]"
  ],
  "checks" => ["outlook"]
})

res = Net::HTTP.start(uri.host, uri.port, use_ssl: true) { |http| http.request(req) }
puts res.code, res.body

Response of GET /v1/jobs/{id}/results (excerpt, test mode: the first item of data):

{
  "kind": "email",
  "input": "re•••@test.mobilevalidate.com",
  "email": "[email protected]",
  "email_status": "valid",
  "e164": null,
  "country": null,
  "checks": {
    "outlook.email": {
      "service": "outlook.email",
      "status": "completed",
      "registered": true,
      "attributes": null,
      "confidence": "high",
      "confidence_score": 0.99,
      "checked_at": "2026-09-25T14:25:53.015Z",
      "cached": false,
      "age_seconds": 0,
      "billed": false,
      "reason": null,
      "poll_after_ms": null
    }
  },
  "test": true
}