Actually, in many corporate cases BOTH parties want to keep the info confidential - the CEO sends over salary details to CFO to load into payroll system. After it's all loaded and printed for the files (or saved in the HR system), they BOTH want it to auto-expire out of their emails, but both are too busy to scrape back through old emails after a month to delete things.
So this confidential mode let's this happen naturally. When the CFO's email is hacked (which it will be eventually at some company) then all is not lost.
Some messages are MUCH more sensitive than others. You might have a default 3-5 year rule (many corps do). That’s way too long for some messages.
especially if sending across an ou boundary where you don’t know the retention treatment this will be great.
Sales teams can be very sloppy w email -> auto import into CRMs, sharing permissions, delegating permissions, running their own optimization apps etc. Because the want to claim credits for sales they don’t like tight retention limits etc
Everywhere I have ever worked has a 30 day email retention policy. This would never change message to message. It’s a regulatory issue and you have no reason to retain messages longer than the minimum so you’re better off enforcing it at the server level.
So this confidential mode let's this happen naturally. When the CFO's email is hacked (which it will be eventually at some company) then all is not lost.
I'm sure many other users will find it useful.