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" : "test@gmail.com" , "is_valid" : true , "mx_valid" : true , "is_disposable" : false , "is_role_based" : false , "quality_score" : 95 , "domain" : "gmail.com" } Enter fullscreen mode Exit fullscreen mode JavaScript Example async…