The subscriber is identified in several ways:
The name= query parameter contains the complete subscriberCode. This only happens when the user receives a verification email and clicks on the link in the email. When a compilete subscriberCode is seen on the name= query parameter, that constitutes verification of the email address.
The sid= query parameter contains an integer subscriberId. This only works for the administrator. It allows the administrator to edit any subscription.
The user is logged into an account other than "nobody" or "anonymous". In that case the notification settings associated with that account can be edited without needing to know the subscriber code.
The name= query parameter contains a 32-digit prefix of subscriber code. (Subscriber codes are normally 64 hex digits in length.) This uniquely identifies the subscriber without revealing the complete subscriber code, and hence without verifying the email address.