How to Detect Disposable Email Addresses in JavaScript (Free API)

Ever had fake signups flood your app with addresses like user@mailinator.com or nobody@guerrillamail.com ? Disposable email services let anyone create a throwaway inbox in seconds. Great for privacy — terrible for your conversion metrics, trial abuse, and email deliverability. Here's how to detect them programmatically using DNS lookups — no third-party blocklist subscription required. The Strategy Instead of maintaining a static list of known disposable domains (which goes stale fast), we'll use a multi-signal approach : MX record analysis — disposable services share mail servers Domain age heuristics — newly registered domains are suspicious Known provider fingerprinting — match MX records against known disposable mail infrastructure Step 1: Look Up MX Records via API We need DNS data for the email domain. Instead of running dig commands, we'll use a free DNS API: async function getDomainDNS ( domain ) { const API = ' https://agent-gateway-kappa.vercel.app ' ; const res = await fetch