It does open msg. Files in both Google Drive and Dropbox – MSG File Viewer Review

App is read only but it does allow you to open files in both Google Drive and DropBox, it is not automatic however, you must press the folder that has an arrow, usually in the right bottom or right top of your screen to tell it what app you want to use to open the file! Great little program. I wish it was written to install on the Samsung Chrome Book as well. I would pay money to buy it!
Review by Roadking555 on MSG File Viewer.