Validate email addresses: RFC-style syntax checks, IDN domain normalization, live MX lookups with A/AAAA fallback (DNS-over-HTTPS), disposable-domain detection, role-address detection (info@, support@), free-provider flagging, and typo suggestions for popular providers (gmial.com -> gmail.com). Single address or batches up to 50. POST a JSON body like: {"emails":["ada@example.com","bad@mailinator.com","typo@gmial.com"]}