It isn't really always clear on what it entails, for example the word "the" will appear in TS documents but you're allowed to use that word without worrying about this happening. Specific pieces of data or groups of data receive a classification based on the harm they can cause if disclosed improperly. However, an entire document receives a classification based on its most sensitive parts so it can be hard to determine what parts of it are actually sensitive. If you don't know, ask, so things like this don't happen. This person should have known better, I can imagine how it's possible to accidently transmit classified data on an unclassified network. But I have a hard time seeing someone make an honest mistake like that 13 times.

What's the point of debating it? The press release seemed to give no information whatsoever that would clue us into motivation.

I would like to see the indictment, if it's not secret itself. There wasn't a link, was there?

Tbh I’d think there would be (technical) mechanisms in place to make this impossible.