Hmm, seems like Google is being burned by their recent "unified" policy and wanting to put everything under a single banner --- their gmail TOS just seems to redirect to the general one. That has a section about "content you submit", but that doesn't seem to apply to email (you don't "submit" your email, do you? If it does apply to email, then it says Google has a license to publish and publicly distribute your email). The Privacy Policy has a section about "Information We Collect", but again email doesn't seem to be covered (nor docs for that matter).

https://mail.google.com/mail/help/intl/en/terms_of_use.html