How to Validate Email Addresses in JavaScript — Deliverability Score API

Regex will not save you. You can validate email format perfectly and still end up with a list full of disposable addresses, catch-all domains, and role-based inboxes that kill your sender reputation.

This guide shows how to do real email validation in JavaScript and Python using a free API that checks MX records, disposable domains, and returns a quality score (0–100) .

The API: Email Validator Pro

👉 Email Validator Pro on RapidAPI

MX record lookup (does the domain actually receive mail?)

300+ disposable domain blocklist (mailinator, guerrilla, etc.)

Role-based address detection (admin@, info@, noreply@)

Catch-all domain detection

Quality score 0–100

Batch endpoint (up to 50 emails)

Sample Response

{ "email" : "[email protected]" , "is_valid" : true , "mx_valid" : true , "is_disposable" : false , "is_role_based" : false , "quality_score" : 95 , "domain" : "gmail.com" }

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