In the previous tip about emailing a PDF without saving it first, you may have noticed another item in the screen shot, called Encrypt PDF. This is a great option for those times when you are sending sensitive information. The Encrypt PDf option creates a password-protected PDF file.
To create an encrypted PDF, simply open the document, hit print, and then select Encrypt PDF from the PDF pull-down menu. You’ll be prompted to enter the password you want to use. Remember that password, because you can’t open the PDF without it. You’ll need to re-enter the password each time you open the file, it’s never permanently unlocked.
The screen shot above is from a file being opened in Apple’s Preview app, but the password protection holds in Acrobat and Reader as well.