Once you understand how it works, there is nothing you cannot do. It’s PGP, installed the way Steve Jobs would have done it. Many want you to install bloated, Windows-like software or, install questionable add-ons. (That’s okay.) Many of the tutorials I found for OS X are not Mac friendly. If you’re not a Mac fan, you won’t understand. There is a certain way of doing things on a Mac. You can encrypt a bash command in Terminal. You can write an encrypted letter in Word. Or, you can encrypt something besides email, you can do that too. If you want to encrypt email, you can use any email program - Mail.app, Thunderbird, Sparrow, Gmail, Airmail. If you install or uninstall apps, PGP will keep working.
Unlike other tutorials for PGP, this tutorial does not care what program you use.