Many malware attacks today occur through a combination of deceitful emails (spam) and compromised web pages. Interacting with spam can put your personal information at risk as well as download a virus to your machine that may spread to other computers on the network. Don't open email from unsolicited sources or unknown email addresses, and take steps to reduce the amount of spam that comes in to your inbox.
Use the Symantec Spam Quarantine service, a service provided by MIT to filter unwanted emails. The service scans all incoming email before delivering it, identifies potential spam using a series of tests, and filters them to the Spam Quarantine server.
Some spam emails are disguised as legitimate with a subject or message designed to catch the untrained "phish." Spoofed sender email addresses, logos, trademarks, and the wording used in the message will often add to the deception. How to identify a phishing email.
Phishing can also occur on a web site that has been cleverly disguised to look like a legitimate site, such as the log in page for a banking web site. After you enter your user name and password, that information is stolen and used to steal your banking credentials.