Email Validation API
Getting started
Subscribe, copy your secret key, and run your first Email Validation lookup.
The Syndaq Email Validation API (v1) performs lightweight, privacy-friendly checks on an email address: format validation, disposable-domain detection, and MX record presence. Each response includes a risk level with reasons you can use at signup or form gates.
What v1 does — and does not do
| Included in v1 | Not included in v1 |
|---|---|
| RFC-style format / syntax checks | Mailbox existence (SMTP RCPT probes) |
| Disposable / temporary domain lists | Catch-all detection |
| MX record lookup for the domain | Deliverability or spam-folder scoring |
| Risk level from those signals | Breach / reputation databases |
v1 is intentionally honest: it helps reject obvious bad input without pretending to verify that a mailbox accepts mail.
What you need
- An Email Validation plan from the Syndaq API catalog.
- A secret key (
ev_sec_) from the Syndaq client area after your order is provisioned.
Email Validation lookups are server-side only. Send your secret key from your backend or trusted worker. Do not embed it in client-side code, mobile apps, or public repositories.
Base URL
All Email Validation endpoints are served from:
https://api.syndaq.com/v1/emailval/Quick start
Replace ev_sec_YOUR_SECRET_KEY with the secret shown in Services for your Email Validation subscription. Email addresses in the path must be URL-encoded.
curl -sS "https://api.syndaq.com/v1/emailval/lookup/user%40example.com" \
-H "Authorization: Bearer ev_sec_YOUR_SECRET_KEY"You can also pass the address as a query parameter:
curl -sS "https://api.syndaq.com/v1/emailval/lookup?email=user%40example.com" \
-H "Authorization: Bearer ev_sec_YOUR_SECRET_KEY"A successful response includes valid_format, disposable, has_mx, and a risk object with level and reasons.
How lookups work
| Step | What happens |
|---|---|
| 1 | Authenticate with your secret key. |
| 2 | Send an email lookup request to the API. |
| 3 | Receive JSON with the result fields (including a cached flag when Syndaq already holds a recent result, plus limits_note for v1 scope). |
Malformed emails that fail basic formatting still return a structured response with valid_format: false and elevated risk when applicable.
Manage your subscription
Sign in to the Syndaq client area and open Services. Select your Email Validation service to:
- View usage and remaining monthly quota
- Copy or rotate your secret key
- Configure optional IP allowlists for API access
Next steps
- Authentication and limits: keys, rate limits, quotas, and IP restrictions
- API reference: endpoints, response fields, and error codes