But here’s a good starting point in
Paragraph 2.b It’s been modified slightly since I last captured this snippet:
[...] you grant to Microsoft a worldwide and royalty-free intellectual property license to use Your Content, for example, to make copies of, retain, transmit, reformat, display, and distribute via communication tools Your Content on the Services [...]
This is a black box proprietary operating system. Called Windows. How do you know anything works according to specification, both intentionally and unintentionally?
You can at least analyze network traffic if you really want to know. If you care enough to do that though, I would think it would be much easier to just not use Windows.