Electronic mail has become the buzz of the town in recent years and while some use e-mail as a means of cheaper and faster ways of sending messages and files over the Internet, it cannot be discounted that some use e-mail as a form of exploit as well, by send unrecognized files to various recipients who in the same way may not know the harmful effects that such files would bring to their personal workstations.
While there are various means of supplying computer protection such as firewalls and anti-virus protection for single and networked computers, some harmful file just tends to get past them. That is why there are specific softwares used for specific infections, particularly the Trojan developed files that do their work unnoticed.
So the next time you get mail from someone who has an attachment with questionable file name extensions, better think twice before clicking or opening it. It may cause more pain than enjoyment in most cases.