Gmail - Allowing Access - Prevent Download/Upload

Good Morning,

We are looking to allow our users to access Gmail, but not allow them to download or upload anything.

I have figured out that I need to use a combination of Cloud App Control policies to allow access to Gmail and then a File Type Control rule to prevent the download/upload of files.

Within File Control rules it works as expected if I block everything except the “Other Documents” category. When I block this category or certain parts then I cannot actually delete emails or save changes to the Gmail page and the format of the page goes strange.

Has anyone successfully achieved this with Gmail and more broadly all webmail sites.

Thanks

Paul