Have you ever received an email with the subject of like this: Paris Hilton Free Video. This has happened to me and to a ton of other people.
What's interesting to notice is the links inside the email. The links called: Microsoft | Unsubscribe | More Newsletters | Privacy... all link to Microsoft websites. Those links are safe, and the spammers (persons who send the spam email) put those links there so the email sounds more realistic, so more folks get tricked that it is an actual real, genuine email from Microsoft.
Why this email contains viruses?
How do I know it. Apart from the fact that it's rare that Microsoft will send an email about Paris Hilton there is something else. This other thing is the big bolg title inside the email: "Paris Hilton Scandal Home Video!" which links to a website. If you click that link, it takes you to a website which automatically infects your computer with a virus.
The link ends up with a exe extension. You can place your mouse above links inside any email (without clicking) and then in your web browser (Internet Explorer, Mozilla Firefox, etc) at the bottom you will see the actual link address. Try this technique on any link inside any website or email.
Links with exe extensions in emails are the most dangerous, these are not websites, or web pages but a downloadable file.
Never click links inside emails that have that exe extension in the end of the website url. So if the email looks really suspicious first check out the links inside the email. Check that they do not end up in exe
I always ask myself the question once I check my emails: Who can the person who sent me this email be? In the case above I instantly got the feeling it's not someone I know or any newsletter I am subscribed to.
If in doubt do not click the links, just check them first. Extreme care and understanding is required with emails that look suspicious.
That's the most common way to get infected by a virus from emails. The other way is through attachments, by opening attachments that are send to you by spammers. These attachments contain viruses. Attachments are simple files/pictures or anything else attached through emails. Your email client like Hotmail, Yahoo Mail etc notifies you when an email has attachments.
Use a popular email client, they have more safety features. Some automatically block spam, sending to junk folder, a common feature nowadays. Other display warning messages when they detect something suspicious. Plus these web based email clients are free.