I have a MAC and my customer has a PC. She downloaded emails into dropbox from outlook, which I downloaded on my computer. The files would not open and asked what app to use to open. I chose outlook. Now, when clicking on the file, it opens an email with the file attached. When I click on the file it opens another email with a file attached. The actual emails uploaded into dropbox and downloaded onto my computer do not open.
Do you happen to know the exact steps that your customer followed to upload her emails to Dropbox? Do you mean that she enabled the Outlook integration to save her email attachments to Dropbox instead, and then she shared them with you?