"Scan" means they take the data out of the "email" silo and use it for purposes other than providing email services to the user (such as using it for advertising).

Searching is not "scanning". Nor is any other normal behavior of providing email services.

So the question at this point is does Google keep your email data silo'd or do they use it for other purposes?

That’s only a dream. Google also scans email snd combines the data with that of all the other users for spam filtering purposes, which is a big part of ‘email’.

It’s not difficult to put together creepy functionality and twist it so one of the purposes is providing email service.

Spam filtering is still in the email silo.

> Searching is not "scanning"

Pray, how does it work, then?

Don't be pedantic. Defining "scanning" as "anything that looks at the bits on disk" makes the word meaningless in this context, because then yes, Google must absolutely "scan" it to provide basic functionality, and heck every service everywhere must "scan" their data to provide basic functionality. But that's not useful to talk about.

Clearly Google Now/Home uses gmail data to be relevant.

Ok, better question: Is Google using your email data for anything not explicitly authorized by and for the benefit of the user?

Have you explicitly authorized them to provide you search and mail-based information in Google Now?

No idea, I don't use Google Now. I hope so, but it wouldn't surprise me if Google "forgot" about that step. But at least that's for the benefit of the user.

According to my understanding of Google's privacy policy, your account data is essentially global by default, they don't need to explicitly ask you service by service where they can use it. IANAL, though.

My point being that "advertising" is a very limited use case. There's nothing necessarily stopping them from selling your scanned, very personal information to anyone.

Their privacy policy is very clear that they don't share personal information, with four exception, none of which include selling it. So, if you trust them, they don't.