Idea from Brandon Mount:
http://www.fastcodesign.com/3052323/hightail-launches-spaces-a-collaborative-file-sharing-tool-for-visual-assets
"With its handy "untangle" feature, you can forward an email to a dedicated address and Hightail will strip the thread of its attachments and dump them all into one "Space.""
http://www.engadget.com/2015/10/15/hightail-spaces-visual-collaboration-commenting/
"Dropbox has had file commenting for a long time, but the differentiator for Spaces is that you can drag over any portion of a document or file and "highlight" it, and then attach your comments specifically to that point. It's kind of a way of footnoting a file and it could make the comments that follow along with it a lot more useful -- instead of just leaving a comment referring to the document at large, you can easily refer to specific parts of the file."