New domain for Sign in with Apple and iCloud+ Hide My Email

Later this summer, Apple will unify the email domains used by Sign in with Apple and iCloud+ Hide My Email under a single shared domain, private.icloud.com, where new addresses for both features will be issued. Existing addresses on the legacy domains (privaterelay.appleid.com and icloud.com) will continue to work; developers should ensure their account systems, email validation logic, and allowlists accept the new private.icloud.com domain.