I don't know - I was able share a link and RSVP without an account. AFAIK I enabled every option other than the shared album. It does prefer contacting via ema

I don't know - I was able share a link and RSVP without an account. AFAIK I enabled every option other than the shared album. It does prefer contacting via email, so it did an email verification via mailed PIN, and then attached that email to the guest list from the link.