Once you send an email to a person, that person owns it and can do whatever he or she wants with it. That person can post it, forward it, and even print it out for distribution. As far as using an office computer goes, it is not your property so you cannot resent that the office reads what you do on it.
I just wonder why people are still being so stupid to make racist comments in public, on the phone, in an email, or anywhere. “Big Brother is watching you,” and it is not the government but your peers, your friends, your co-workers, complete strangers around you. Come on! Get a grip! There is no privacy with phones, computers, tablets, email, etc. It is not going to get any better. The way technology is going, I expect it to get worse.