We have always known that as long as you don’t “execute” or “click” on an attachment in an email you’ll be pretty safe. Of course if there’s HTML in a newsletter that is running some program or script you can get infected, but you can prevent this from happening by not having your email program automatically execute a script.
However, hackers are now working to put a virus in a graphic file. This means all you have to do is open an email message to get infected.
Washington Post writes Hackers are close to finding a way to spread harmful computer viruses just by getting people to open an e-mail message or visiting an infected Web site, computer security experts warned yesterday.
The hacking community, they said, is developing tools to exploit a new security flaw in computers running Microsoft’s Windows XP and Server 2003 operating systems. Those tools could be used to power the worm, which could allow attackers to take control of people’s computers. Microsoft identified the flaw last week and offered a free software patch to fix it.

Ensure you keep your computer updated with the latest updates from Microsoft