This is great for sysadmins! Now if only us users had the option of turning it off without asking our sysadmin!
This horrendous decision is due to Microsoft's decades-long complete and utter cluelessness about the primary importance of user needs over the day-to-day control of IT. It's staggering to me that after all these years, Microsoft has STILL failed to change, and clearly didn't even do basic user research to figure out how millions upon millions of users would feel and react to this. It is the stupidest decision to make this feature incapable of being changed by ordinary users. I can no longer see what meetings I have that have been set up by clients. My calendar says EXTERNAL EXTERNAL EXTERNAL across my entire week. My emails can no longer be scanned because the subject line now reads EXTERNAL EXTERNAL EXTERNAL down the entire Inbox. This is corporate stupidity about end users and lack of basic user research at a level I have not seen since the mid-1990s.