Dropbox

Due to how Dropbox maintains file states, there are some limitations with applying API policy actions:

• Files which are only shared with non-Dropbox users (aka externally shared files) will be considered private. This is because the user exists outside of Dropbox and cannot access the file until they register an account with Dropbox. Once Forcepoint ONE SSE sees the external user as a valid user, the file will be identified as external and acted on accordingly.
• Dropbox public share view link (i.e. generating a shareable link that can be sent to anybody) automatically removes all member specific sharing and state information pertaining to the members. This means that a file that was shared with external users will drop information about those users if a user then generates a shareable link on that file. Once this occurs, if Forcepoint ONE SSE policy is set to remove share on the file then Forcepoint ONE SSE will set that file to private since the original state and specific member sharing information was removed by Dropbox.