I just upgraded to Dropbox Professional (perhaps in error?) because I read that with that version it would be possible to determine who (if any) on my email list might have viewed a shared file link provided in the text of my email message. Thus far the Dropbox site says to hover over a gray avatar or something but I see no such item, and it is very unclear just how to find such an avatar or how to complete my inquiry and/or view the entire "history" which supposedly also includes access data etc.