I'd argue Gmail is a social network. Facebook just makes it a little easier to share images, videos, etc. I don't think it's a difference in kind but of degree.

I'd argue Gmail is a social network. Facebook just makes it a little easier to share images, videos, etc. I don't think it's a difference in kind but of degree. When I send an email to someone, I expect it to only go to that one person. Sure, there are some cases where it might be okay for the receipient to share it, and usually they have an understanding ahead of time of whether it's okay or not. But the sender usually considers it a violation of privacy if it is forwarded to third-parties, especially to the general public. If Google one day unilaterally decided to make all your Gmail email publicly viewable and searchable, there would be a shit storm. Yes, in theory before your emails could have been made public. But in practice, 99% of them do not and it would only have happened if the sender or receiver caused it to happen. But in this case, the trusted intermediary service caused it to happen. That's the violation. So I think the Gmail example is valid and relevant.