Let's talk about Junk email AKA Spam. You may have noticed an influx of junk mail recently, if not consider yourself lucky. Below is a great blog that explains why blocking emails is almost hopeless these days. Also, ever try to block someone and it says it is an invalid email address and is unable to block?
These spammers are getting smart and will try everything to get emails out in the hopes you will open, unsubscribe (confirms your email is valid), or click on a link. Never do this! All you should be doing is marking it as junk or filtering the email to your junk folder.
Read an interesting blog by Leo Notenboom, which explains this in more detail by clicking the link below.