The continuing proliferation of the Internet has enabled more and more people to take advantage of electronic mail (e-mail). Unfortunately some unscrupulous individuals or agencies take advantage of the email’s vulnerabilities to spread computer malware (such as trojans, viruses, and worms) that can damage a computer system or perform ‘phishing attacks,’ which are attempts to trick a person into disclosing personal information such as bank account details with the intent of theft and fraud.
Do not open an email that came from an unknown person, or if its subject heading is something suspicious like 'you won' or 'a system error occurred.' These types of emails are usually ploys to trick you to send personal details or install rogue/fake software that can either destroy your computer or turn it into a member of an infected botnet.
Avoid downloading and opening attachments that you did not expect to get in the first place. Word files and PDFs are common transports of malware.
Be careful about what links you click on. You can be directed to websites that contain can install viruses and other malware.