Why regex fails at email validation and what developers should use instead

A software developer argues that regex-based email validation, widely used across codebases, is fundamentally insufficient for confirming whether an address is real or deliverable. Common regex patterns approve disposable addresses, misspelled domains, and role-based inboxes while missing critical deliverability signals. The developer recommends a layered approach covering syntax checks, disposable and role-address detection, typo suggestions, and DNS MX record lookups to verify that a domain can actually receive mail. MX checks require a DNS query rather than a simple string test, which is why many developers skip this step despite it being among the most effective filters. The author has built and shared a free API endpoint on Cloudflare Workers that bundles all four validation layers into a single GET request with no signup required.