> For example, if the government purchased Outlook licenses, I'd assume DoD can read clerks' emails, but Microsoft employees can't.

Funny, my automatic assumption when using any US based service or US provided software is that at a minimum the NSA is reading over my shoulder, and that I have no idea who else is able to do that, but that number is likely > 0. If there is anything that I took away from the Snowden releases then it was that even the most paranoid of us weren't nearly paranoid enough.