Even if an email appears to have been sent by someone you know, it may be a fake. Some of the current viruses hijack the address books of an infected computer, spamming all the names with a bogus email to spread the virus.My son's father-in-law received an email inviting him to "friend" an acquaintance on the Tagged social network. Within minutes of his responding, everyone in his address book received a similar email from him. He's still sending out apologies.
One of the latest scams is fake notices of Microsoft Updates. The email looks official and urges you to click a link to update your copy of Microsoft Outlook or Outlook Express. But if you click it, you get an infection. Some of the perpetrators have even been clever enough to append their malicious computer code to a pirated copy of legitimate software updates. Probably the best defense is to activate the automatic updates feature of your programs, and to ignore emails with links to download updates. If you think the offer is legitimate, try browsing directly to the software publisher's website and downloading the upgrade there, where you can be confident that it is legitimate.
Dancho Danchev, writing for Ziff Davis says, "With a well known pattern of abusing the momentum advantage for malicious purposes by hijacking emerging news stories or events ... it shouldn’t take long before Iran’s massively covered election starts appearing in malicious campaigns."