Microsoft Office 365 introduced Office Intelligent Services at least as far back as 2016, These are cloud-enhanced features on the Office applications Word, Outlook, Excel and PowerPoint meant to aid the user. I only noticed this last month, i.e. September 2018, when Office 365 updates on my Macintosh each flashed a window about turning on “Intelligent Services”. I dismissed those but went on to check.
With the Office Intelligent Services option turned on, it appears that document content would be accessed by Microsoft. Even if it is Microsoft policy to not use this data for other purposes, this poses a problem for confidential data. I have kept that data off any cloud service, including the ones provided by NUS. This option, however, circumvents that control of privacy with any Office document.
Happily, Office Intelligent Services can be turned off within the preferences settings of each of the Office applications. Just go to Preferences > Privacy (in earlier versions this is “Security & Privacy”) > unselect Enable services, like so:
I process student data intermittently, so I keep this option turned off. After checking in on colleagues, a couple of Mac users had this option turned on, without them being aware of having opted in or of its significance. This is a problem, so I’ve suggested to NUS IT that they explain this to users.
It was suggested that I might be prompted every now and then by Office 365 to turn Office Intelligent Services back on. That would be terrible, but it’s been two months since, and not word from the suite!
Otterman speaks... 
Companies, Google and Microsoft for example, want access to your emails, data and documents, especially when you use a software client from one company to access the email service of another. Enforcing “intelligent services” in an application is another repackaged way around personal privacy laws.