I clearly skipped that line.

In the web interface, there's no way to do this although right-click and "edit as new" would be close - you would be able to choose that and send yourself a 'copy' which can then be moved. This is likely not what she wants, but then tags is what she wants, she just doesn't know it yet.
Aside from that, a standard IMAP client or Outlook via connector, but I appreciate the desire to keep people out of third party software.