Email checker online API

REST API for email validation

Use the single validation endpoint to verify deliverability, DNS records, and domain reputation. No API key is required for basic usage; keep requests within fair limits.

Base URL

https://email-checker-online.com

Rate limit guidance: up to 30 requests per minute for single checks. For higher limits or custom integrations, please contact support.

Single email validation

Performs syntax check, MX record lookup, SPF lookup, and a live SMTP mailbox check (best-effort — some providers block verification, which we report honestly).

Endpoint

POST /api/validate-single

Request Body

{
  "email": "user@example.com"
}

Response Fields

Field	Type	Description
valid	boolean	Overall deliverability status
status	string	Status code: `valid`, `invalid`, `risky`, `disposable`, `uncertain`
formatValid	boolean	True if the email syntax is correct
mxValid	boolean	True if valid MX records were found
smtpValid	boolean	True if the mailbox was confirmed to exist
isCatchAll	boolean	True if the domain accepts all emails (Catch-all)
disposable	boolean	True for disposable/temporary email domains
spf.valid	boolean	True if SPF records are configured

Response Example

{
  "email": "user@example.com",
  "valid": true,
  "status": "valid",
  "formatValid": true,
  "mxValid": true,
  "smtpValid": true,
  "isCatchAll": false,
  "disposable": false,
  "spf": {
    "valid": true,
    "record": "v=spf1 include:_spf.google.com ~all",
    "message": "SPF record found"
  },
  "message": "Valid email address",
  "details": {
    "format": { "valid": true, "domain": "example.com" },
    "mx": { "valid": true, "records": [{ "priority": 10, "exchange": "aspmx.l.google.com" }], "message": "Found 1 MX record(s)" },
    "smtp": { "valid": true, "host": "aspmx.l.google.com", "message": "Mailbox exists", "rcpt_code": 250 }
  }
}

Error responses

429 Too Many Requests

Back off and retry after the time specified in the Retry-After header.

400 Bad Request

Invalid email or domain format. Fix input and try again.