I did a presentation on Internet security to my Toastmasters club, Hillcrest Toastmasters recently.  Several people asked me for a copy of the slides so that they could take some of the actions that I discussed. The presentation covers why to set up S/MIME certificates for sending and receiving digitally signed and encrypted email.  It also covers why you should use HTTPS as a user and as a web site administrator.

Detailed instructions on how to set up the email security settings are described in two more recent articles: