Everyone can read your private email
All your email will eventually be online in an easily searched database. Just ask JB at Enron, who at 7:42 pm on April 6, 2001 asked CG to “serve me lunch in bed and sing me a lala bye before I start the night shift.”
How do I know? I searched the Enron Explorer for “lunch”.
Every new employee at Logos Bible Software goes through an email training class that covers style, etiquette, and the fact that your business email isn’t private. You can preview it online and download it for adapting to your organization. (There are notes for the presenter on most of the slides.)