Email scams are very common these days. You may receive an email from a bank asking you to confirm your account details or perhaps you have received an email from someone claiming to have seen your profile on a social networking / daing website and wants to chat with you.
The most common reason for this happening is that someone you have spoken with by email has had their personal online address book hacked. This is extremely widespread these days especially with free emails such as Yahoo, Hotmail, Gmail etc.
A quick look on Google will show how widespread this is. Or see the links below
Once an account is hacked, "automated bots" read the email subjects and sends emails out to everyone in the address book hoping that the spam email may apply to some of the recipients. This is the reason why people receive emails from banks they arent even a customer of asking them to verify their account.
Obviously dont respond to any email directly sent to you unless you know the sender and simply delete the email.