This article is based on the ESET antivirus, but the instructions will be similar for most other professional anti-viruses as well.
A Virus as an attachment
Unlike many people think, as long as you are using an up to date version of Outlook, simply opening or reading an email in the preview pane is unlikely to infect your computer, but opening an attachment with a virus will certainly infect your computer. The emails themselves are designed to trick you into opening the attachment using all sorts of different stories and techniques. Some examples are emails making out to be from a post office with a form attached you need to fill out to receive a package that has been sent to you, or another common email is one with an invoice or statement attached saying payment is overdue. There are many variations, but the one thing in common is that they have an attachment with a virus in it.
Make sure Email protection is turned on
If you receive an email with a suspect attachment, do not open it. Instead right click the attachment and select “Save As” and save it to your desktop. Now go to your desktop, do not open the file, but right click it and select “Scan with Eset”. The antivirus will check the file and very quickly tell you whether the file is safe to open or not. If the file does contain a virus, it will most likely be deleted by the antivirus program, but it will need to be immediately deleted from Outlook manually. When deleting the email in Outlook, press the Shift key with the Delete key so it is completely removed rather than just sent to the Deleted Items folder.