Nowadays it’s smart to think cautiously BEFORE you open any emails from sources whom you do not recognize. Why?? PHISHING ! Below is a description I found in Wikipedia.
Phishing is a way of attempting to acquire sensitive information such as usernames, passwords and credit card details by masquerading as a trustworthy entity in an electronic communication. Communications purporting to be from popular social web sites, auction sites, online payment processors or IT administrators are commonly used to lure the unsuspecting public. Phishing is typically carried out by e-mail spoofing or instant messaging,
 It often directs users to enter details at a fake website whose look and feel are almost identical to the legitimate one. Phishing is an example of social engineering techniques used to deceive users.
 Exploits the poor usability of current web security technologies.
 Attempts to deal with the growing number of reported phishing incidents include legislation, user training, public awareness, and technical security measures.
Take a look at the guidelines provided by APWG in order to learn how to protect yourself from this type of Internet crime.
Anti-Phishing Working Group
The Anti-Phishing Working Group (APWG) is the global pan-industrial and law enforcement association focused on eliminating the fraud and identity theft that result from phishing,pharming and email spoofing of all types.