BYTETOOLS

Mailcheck.ai API

Free email validation API with no key: check format, MX records, domain age and whether an address is disposable, in a single request. Tested example.

No API key requiredCORS enabledHTTPSFree tier

Endpoint tested and returned HTTP 200 on 2026-08-19

What is the Mailcheck.ai API?

Mailcheck.ai is a free, key-free email validation API that checks address format, verifies MX records exist, reports domain age and flags disposable email providers in a single request.

Mailcheck combines several validation signals that usually require separate services: syntax, MX record presence, domain age and disposability. Getting all four in one call makes signup validation considerably simpler.

Domain age is the interesting differentiator. Freshly registered domains correlate strongly with throwaway and fraudulent signups, so `domain_age_in_days` is a useful risk signal that pure disposability lists miss entirely.

Quick facts

Base URL
https://api.mailcheck.ai
Authentication
No API key required.
Rate limit
No published hard limit; fair use expected.
Pricing
Free.
CORS
Enabled — callable directly from browser JavaScript
Official docs
Read the docs

How to use the Mailcheck.ai API

Every request below was executed against the live API on 2026-08-19, and the response shown is the real body it returned — not an illustration.

1. Validate an email address

GET https://api.mailcheck.ai/email/test@gmail.com

curl
curl 'https://api.mailcheck.ai/email/test@gmail.com'
JavaScript (fetch)
const res = await fetch("https://api.mailcheck.ai/email/test@gmail.com");
if (!res.ok) throw new Error(`Request failed: ${res.status}`);
const data = await res.json();
console.log(data);
Python (requests)
import requests

res = requests.get("https://api.mailcheck.ai/email/test@gmail.com", timeout=20)
res.raise_for_status()
print(res.json())
Response — HTTP 200
{
  "status": 200,
  "email": "test@gmail.com",
  "normalized_email": "test@gmail.com",
  "domain": "gmail.com",
  "domain_age_in_days": 11329,
  "mx": true,
  "mx_records": [
    {
      "hostname": "gmail-smtp-in.l.google.com",
      "priority": 5
    },
    {
      "hostname": "alt1.gmail-smtp-in.l.google.com",
      "priority": 10
    },
    {
      "hostname": "alt2.gmail-smtp-in.l.google.com",
      "priority": 20
    },
    {
      "hostname": "alt3.gmail-smtp-in.l.google.com",
      "priority": 30
    },
    {
      "hostname": "alt4.gmail-smtp-in.l.google.com",
      "priority": 40
    }
  ],
  "mx_providers": [
    {
      "slug": "google",
      "type": "mailbox",
      "grade": "professional"
    }
  ],
  "spf": "relaxed",
  "dmarc": "none",
  "disposable": false,
  "public_domain": true,
  "relay_domain": false,
  "free_subdomain": false,
  "alias": false,
  "role_account": true,
  "spam": false,
  "did_you_mean": null
}

Parameters

ParameterTypeRequiredDescription
email/<address>pathOptionalValidate a full email address. test@gmail.com
domain/<domain>pathOptionalValidate a domain only. gmail.com

Response fields

statusinteger
Response status code inside the body.
email / normalized_emailstring
The address checked and its normalised form.
domainstring
Domain portion of the address.
domain_age_in_daysinteger
Age of the domain registration — a useful fraud signal.
mxboolean
Whether the domain has MX records and can receive mail.
disposableboolean
Whether it is a known throwaway provider.
mx_recordsarray
The actual MX hosts with priorities.

What you can build with the Mailcheck.ai API

  • Validate email addresses at signup before sending anything
  • Flag newly registered domains as higher risk
  • Reject addresses that cannot receive mail, cutting bounce rate
  • Block disposable providers on paid tiers

Common errors and how to fix them

mx: false

The domain has no mail server configured.

Fix: Mail will bounce — reject at signup rather than sending and failing.

Very low domain_age_in_days

The domain was registered recently.

Fix: Not proof of fraud, but a reasonable trigger for extra verification.

Normalised address differs

Some providers ignore dots and plus-addressing.

Fix: Use normalized_email for deduplication so user+tag@gmail.com does not create multiple accounts.

Mailcheck.ai API — frequently asked questions

Is Mailcheck.ai free?

Yes, free with no API key required.

What does it check?

Address format, whether the domain has MX records and can receive mail, how old the domain registration is, and whether it is a known disposable provider — all in one request.

Why does domain age matter?

Freshly registered domains correlate strongly with throwaway and fraudulent signups. It is a risk signal that disposability lists alone do not capture.

What is normalized_email for?

Deduplication. Gmail ignores dots and plus-addressing, so user+tag@gmail.com and u.ser@gmail.com are the same mailbox. Use the normalised form as your uniqueness key.

Tools that pair with this API

JSON Formatter

Format, beautify and minify JSON online with 2-space, 4-space or tab indentation. Sort keys alphabetically and catch syntax errors instantly — free and private.

Mailcheck.ai is an independent third-party service and is not affiliated with ByteTools or ByteVancer. Details on this page were verified on 2026-08-19; always check the official documentation before relying on this API in production, as terms and limits can change.