Today’s internet is full of people who want to do bad things – or what we as genealogists consider bad.  In addition to those who want to collect all the information they can about you to use, there are those who just want to see how much they can mess up the internet.  These folks are ever evolving that nasty bunch of programming we call “virus” or “worm”.  Now, lets say sends you and email and they are 120% sure they sent a “clean” email, so you then decide to open it.  Do Not before scanning it yourself.  The reason is that some new bad programs can attach “in transit”.  Always be careful, unless you like dealing with any symptoms your computer may exhibit once infected.