Comment by Dibby053

My guess would be it has nothing to do with email itself. Maybe it's some iCloud API that accepts obfuscated emails but returns the original email in the response, or an ID which can be used to retrieve the iCloud email from another API endpoint. Could be as simple as an "add contact/friend" feature in some Apple product (like a mail client, or a file sharing service) that resolves the obfuscated email to the original iCloud account.