Dropbox has no proper means to send an email to complain or file a report. I received an email from no-reply@em-s.dropbox.com. The subject was "Please don't ignore: Your setup isn't complete". I know this account was set up over 5 years ago. While I may not use it as often as other accounts I know that it is completed. With that suspicion I logged into my account using an official Dropbox bookmark I created and nothing ... no messages on my account ... no notifications. Therefore, I am positive that this email was a fishing scam.
Please send and/or have proper means for customers to report issues.