For zcash currently, yes. But for the underling tech, no. You scan the blockchain in Zcash to be notified of a payment. But the sender could just as easily send

For zcash currently, yes. But for the underling tech, no. You scan the blockchain in Zcash to be notified of a payment. But the sender could just as easily send you an out of band message with everything you need to know to spend the money and find the payment. There's even a draft spec for doing it for Zcash. https://github.com/zcash/zips/pull/420/files#diff-635022fa4a51619d899746b1d35f47790cbee665059c85d22cc12b64fd77c750 https://github.com/zcash/zips/pull/420/files#diff-635022fa4a...