Validate email

Validate email is an API that checks whether an email address has a correct format and, optionally, whether its domain has records set up to receive mail (MX), right before you save it to your database or send it something.

How it works

You send the email and it checks two things: the format (the same criteria browsers use for an email-type field) and, if the format is correct, whether the domain actually has MX records. It doesn't send any email or check that the specific account exists, only that the domain is set up to receive mail.

An invalid email isn't a request error: the response is 200 with "valid": false, same as when it's valid.

All you need

Your API key. Create it in your dashboard with "+ Create key". It's shown only once, so copy and save it.
In your automation platform, an "HTTP Request" step (n8n, Make, Zapier, Pipedream… all have one).

How to use it in n8n (step by step)

In the HTTP Request node:

Method: POST
URL: https://api.cofferdock.com/validate-email
Send Headers: on → add two: x-api-key = your key, and Content-Type = application/json
Send Body: on → Body Content Type: JSON → { "email": "customer@example.com" }

In Make (HTTP → Make a request module): same method and URL, Body type: Raw, Content type: JSON, with the same body.

Options (inside the JSON)

Option	Default	What it does
`email`	-	Required. The email to validate.
`check_mx`	`true`	Set to `false` if you only want the format checked, without querying the domain (faster).

API overview

Endpoint: POST https://api.cofferdock.com/validate-email
Auth: header x-api-key: YOUR_KEY.
Input: application/json ONLY.
Format: the WHATWG living standard regex (the one behind <input type="email">) plus an extra check that the part before @ doesn't start/end with a dot or contain two dots in a row.
MX: Node's native dns.resolveMx with its own 5s timeout. Never returns a 500 for a DNS problem: if the lookup fails or times out, mx_found comes back null (unknown) instead of forcing a false, and valid doesn't drop just because of that.
Limits: 30 requests/min per IP. 1 call = 1 credit, whether the email is valid or not.

Options

Option	Default	Description
`email`	-	Required. Non-empty string, up to 254 characters.
`check_mx`	`true`	Boolean. If `false`, the domain's DNS isn't queried.

Possible `reason` values

Value	Means
`invalid_format`	The email's format isn't valid.
`no_mx_records`	The domain has no MX records (or doesn't exist).
`null_mx`	The domain explicitly publishes that it doesn't receive mail (RFC 7505).
`mx_lookup_timeout`	The DNS lookup took longer than 5s. `mx_found` stays `null`.
`mx_lookup_failed`	Network error while querying DNS. `mx_found` stays `null`.

Examples

curl:

curl -X POST "https://api.cofferdock.com/validate-email" \
  -H "x-api-key: YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{"email":"customer@example.com"}'

JavaScript (Node 18+):

const r = await fetch('https://api.cofferdock.com/validate-email', {
  method: 'POST',
  headers: { 'x-api-key': 'YOUR_KEY', 'Content-Type': 'application/json' },
  body: JSON.stringify({ email: 'customer@example.com' }),
});
const { valid, mx_found } = await r.json();

Python:

import requests
r = requests.post(
    'https://api.cofferdock.com/validate-email',
    headers={'x-api-key': 'YOUR_KEY', 'Content-Type': 'application/json'},
    json={'email': 'customer@example.com'},
)
print(r.json())

Response

{ "success": true, "valid": true, "format_valid": true, "mx_found": true, "domain": "example.com",
    "meta": { "used": 12, "remaining": 488 } }

What you get back

valid is the overall verdict; format_valid and mx_found tell you separately what failed if valid is false, and reason explains it in one word.