My impression of the gmail spam blocker whitelist/blacklist system is that the whitelist is simply your contact list.
So – when you get an email from someone in your contact list (which gmail automatically adds people to whenever you send them email), it is never going to be marked as spam.
When you click ‘Not spam’ I think gmail just adds the sender to the contact list.
So, you inadvertantly probably have a considerable-size whitelist in gmail just through normal gmail use even if you never used the “not spam” button.
I’m not aware of any blacklist that it uses or lets you access.
I may not know what I’m talking about