No matter how technically savvy you consider yourself to be, there's always a good chance you will come across something that you just don't know anything about. For instance, a few of us at Windows Central were chatting online, and someone asked what S/MIME is and whether they should enable in their email settings on their Windows phone.
Having worked in IT for a number of years, I had heard the term S/MIME before. However, I didn't know nearly enough about it to answer the questions. Immediately, we all agreed that it was a good idea for a post. What you now have before you is an attempt to explain what S/MIME is and help guide you in deciding if it is something you should use on your Windows phone.