When This Blows Over

…It is impossible to paste a classified document into an unclassified
email accidentally, because the three computer systems (Unclassified,
Confidential/Secret, and Top Secret) are physically separate networks,
each feeding into an independent hard drive on the user’s desk. If a
classified document appears in an unclassified email, then someone
downloaded it onto a thumb drive and manually uploaded it to the
unclassified network — an intentional act if ever there was one.
One of Clinton’s emails suggests that downloading and uploading
material in this fashion was a commonplace activity in her office. In
June 2011, a staffer encountered difficulty transmitting a document to
her by means of a classified system. An impatient Clinton instructed him
to strip the classified markings from the document and send it on as an
unclassified email. “Turn into nonpaper w no identifying heading and
send nonsecure,” Clinton instructed.
On three separate occasions staffers got sloppy and failed to strip the
“nonpapers” of all markings that betrayed their classified origins.