Reasons for solid spamfilters, awareness of what not to click or open in your inbox (come on, folks, when has porn in your inbox ever indicated good things on the way?), and deleting stuff you didn't ask for (sometimes even if you know the source...).
Safe internet habits are a requirement. I actually got something very similar to that the other day (based on the Subject line); don't know what was in it as it was summarily executed by the firing squad.

LM