Gross. All corporate emails are surveilled. Corporate computer "security" professionals that advocate for using Microsoft products are LARPs.
Ironically, including me. The software I am making for my client will need to run in Microsoft Azure. I have no illusions about the fact that all of my client's confidential, proprietary, trade secret data that will flow through that application will be surveilled, analyzed, etc. by Microsoft. But they don't care. No one cares.