Do you know if Not Spam works locally or globally? Assume I'm emailing Alice and Bob and get flagged as spam. Alice checks her spam folder every day and keeps flagging my mails as not spam. Bob just assumes Google's spam filter works and has never looked in his spam folder. Will my emails eventually get through to both Alice and Bob or just to Alice?
I'd bet with fairly high odds (and hope) Gmail whitelists locally. If Alice thinks your mails aren't spam but Bob does, I would want Alice to get your mails normally but Bob to be able to keep ignoring you, implying a need for local blacklists and whitelists with a reasonable set of defaults. If Alice + some large number of others think you're alright, maybe you'll be promoted to not being flagged as spam by default. Bob might then just have to take the action of marking your things as spam to invoke a (hopefully) local spam/blacklist rule.
There are a few functions which whitelist locally like adding someone to your contacts. But I think "Not Spam" moves it to the inbox and provides feedback into the voting algorithm without whitelisting at any scope.
