Email Verify API

A free, open source REST API to verify email addresses in real time. Check syntax, DNS MX records, and detect disposable email providers — no account required.

✓ Free & Open Source ✓ No API Key Required Self-Hostable MIT License

How it works

Each verification runs three independent checks:

Check	What it does
Syntax	Validates the email format against RFC 5322 rules (local part, @, domain).
MX Record	Performs a live DNS lookup to verify the domain can actually receive emails.
Disposable	Checks the domain against a curated list of 60+ known disposable/temporary email providers.

⚠️ This API does not perform SMTP handshake verification (no actual connection to the mail server). MX check confirms the domain is configured to receive email, not that the specific mailbox exists.

Base URL

All endpoints are relative to the base URL of your deployed instance.

https://email-verify-api.onrender.com

All responses are application/json. All requests must use HTTPS.

Authentication

🔓 This API requires no authentication. All endpoints are publicly accessible. CORS is enabled for all origins.

If you self-host this API and want to add authentication, you can add an API key middleware to main.py.

Rate Limiting

The public hosted instance applies the following limits to ensure fair usage:

Endpoint	Limit
`POST /verify`	60 requests / minute per IP
`POST /verify/batch`	10 requests / minute per IP
`GET /check-domain/{domain}`	60 requests / minute per IP
`GET /is-disposable/{domain}`	120 requests / minute per IP

When a rate limit is exceeded, the API returns HTTP 429 with a Retry-After header.

Endpoints

POST /verify Verify a single email address

Request Body

Field	Type	Required	Description
`email`	string	required	The email address to verify.

Example Request

curl -X POST https://email-verify-api.onrender.com/verify \
  -H "Content-Type: application/json" \
  -d '{"email": "user@example.com"}'

Example Response — Valid

{
  "email": "user@example.com",
  "valid": true,
  "syntax_valid": true,
  "mx_valid": true,
  "disposable": false,
  "details": {
    "domain": "example.com",
    "mx_records": ["mx.example.com"]
  }
}

Example Response — Disposable

{
  "email": "test@mailinator.com",
  "valid": false,
  "syntax_valid": true,
  "mx_valid": true,
  "disposable": true,
  "details": {
    "domain": "mailinator.com",
    "mx_records": ["mail.mailinator.com"]
  }
}

POST /verify/batch Verify up to 20 emails at once

Request Body

Field	Type	Required	Description
`emails`	string[]	required	Array of email addresses. Max 20.

Example Request

curl -X POST https://email-verify-api.onrender.com/verify/batch \
  -H "Content-Type: application/json" \
  -d '{"emails": ["user@example.com", "test@mailinator.com"]}'

Example Response

{
  "count": 2,
  "valid_count": 1,
  "results": [
    {
      "email": "user@example.com",
      "valid": true,
      "syntax_valid": true,
      "mx_valid": true,
      "disposable": false,
      "details": { "domain": "example.com", "mx_records": ["mx.example.com"] }
    },
    {
      "email": "test@mailinator.com",
      "valid": false,
      "syntax_valid": true,
      "mx_valid": true,
      "disposable": true,
      "details": { "domain": "mailinator.com", "mx_records": ["mail.mailinator.com"] }
    }
  ]
}

GET /check-domain/{domain} Check MX records for a domain

Path Parameters

Parameter	Type	Description
`domain`	string	Domain name to check (e.g. `example.com`).

Example Request

curl https://email-verify-api.onrender.com/check-domain/gmail.com

Example Response

{
  "domain": "gmail.com",
  "mx_valid": true,
  "mx_records": ["alt1.gmail-smtp-in.l.google.com", "gmail-smtp-in.l.google.com"],
  "disposable": false,
  "can_receive_email": true
}

GET /is-disposable/{domain} Check if a domain is a disposable email provider

Example Request

curl https://email-verify-api.onrender.com/is-disposable/yopmail.com

Example Response

{
  "domain": "yopmail.com",
  "disposable": true
}

GET /health Health check

{ "status": "ok" }

Error Codes

Code	Meaning	Common Cause
400	Bad Request	Missing or empty `email` field, batch exceeds 20 items, invalid domain.
404	Not Found	Route does not exist.
429	Too Many Requests	Rate limit exceeded. Check `Retry-After` header.
503	Service Unavailable	Internal DNS resolution failure.

Error Response Format

{
  "detail": "Email cannot be empty."
}

Legal & GDPR

Data Retention

This API processes email addresses in memory only. No data is stored, logged, or shared with any third party. Each request is stateless — no database writes occur.

GDPR Compliance

Because no personal data is persisted, this API operates as a pure processing tool with no data retention obligations under GDPR Article 5(e). Integrators are however responsible for their own GDPR compliance when collecting email addresses from end users.

DNS Queries

MX record lookups are performed against public DNS servers. The domain portion of the email (never the full address) is transmitted as a standard DNS query. This is equivalent to any other DNS resolution and does not constitute personal data processing under GDPR.

Acceptable Use

This API may not be used for spam, phishing, or any unlawful purpose. Bulk harvesting or scraping of email validation results to build databases is prohibited.

License

Source code is released under the MIT License. You are free to self-host, modify, and redistribute.

Self-Hosting

Run locally

git clone https://github.com/your-username/email-verify-api
cd email-verify-api
pip install -r requirements.txt
uvicorn main:app --reload

Interactive docs available at http://localhost:8000/docs

Deploy on Render

The repository includes a render.yaml file. Simply connect the repo to a Render Web Service — it will auto-detect the configuration.

Deploy on Railway / Fly.io

Any Python-compatible hosting works. Start command:

uvicorn main:app --host 0.0.0.0 --port $PORT