Function extractEmailDomain

apps/web/src/lib/email-domain.ts:35–43

(email: string)

 * boundary — so a stale PSL is low-impact.
 */
export function extractEmailDomain(email: string): string | null {
  const atIndex = email.lastIndexOf('@');
  if (atIndex === -1) return null;
  const host = email.slice(atIndex + 1).toLowerCase();
  if (host.length === 0) return null;
  const registrable = getDomain(host, { allowPrivateDomains: true });
  if (registrable !== null) return registrable;
  return `${host}.invalid`;
}