Beware of all attachments. Do not assume that e-mail from a friend is to be trusted. The friend may be an unwitting victim of a Trojan or worm that is using his or her address book to send out malicious mail. Never open an attachment with the extension .exe without doing a virus scan, and even then, only when you are sure what the file is. Better, never open any attached file without doing a virus scan.
Many file types can contain dangerous code.
In addition, extensions can be faked and executable files may be disguised to seem harmless. Unfortunately, even the body of a message may contain evil-doing scripts or code if it is in HTML format. Even if you only preview a message, it may cause the scripts or code to be executed. Then select the Restricted Sites icon and select Custom Level. Click the Settings button.