Whoever knew to jump the air gap knew to strip the markings.
This will tell them who sent what to whom and when.
Funny thing about government scanners... most are network jobs that email you the document. If someone scanned the marked version and used Adobe to strip it, that info will be found.
Someone somewhere has a lawyer on speed dial.
Yep. They just need a trail to follow. Having the electronic copies of the emails with the message headers intact will establish an audit trail. I'm pretty sure that's at least part of the reason Hillary had those emails printed off instead of just sending them the files. Printed emails don't include the headers.