What you should know about opening files from the Internet or e-mail
The most common way for computer viruses to spread is through files that you get from the Internet or e-mail. So before you download a file or click an e-mail attachment, consider:
Does that file have a virus?
You won't know unless you check. Make sure you have an antivirus program installed and that it is up to date and set to scan all incoming e-mail attachments and downloaded files. Keeping your antivirus program up to date improves its chances of catching the latest known virus.
If you do not have antivirus software installed, you should purchase and install an up-to-date antivirus program to help protect your computer. For a list of popular antivirus programs, see Microsoft Antivirus Partners (http://www.microsoft.com/security/partners/antivirus.asp).
What do you know about that e-mail attachment?
Before you open an e-mail message or attachment, consider:
Do you know and trust the sender of the e-mail message? If you get e-mail from a person or business you’ve never heard of before, you should be cautious.
Have you exchanged e-mail with this person before? If you get e-mail from someone you know but have never corresponded with, ask yourself if there is any reason you’re getting this message now—especially if the message has a file attachment or contains a link to a Web site.
Do you have any reason to expect e-mail from this person? If you are surprised to see e-mail from this person, be cautious about opening the message.
Does the message on the subject line make sense coming from the sender? If the subject line is just gibberish or nonsense, you’ll be safer if you delete the message.
If the answer to all of the questions above is no, it's probably best to delete the message.
If you know the sender of the message but the message looks suspicious, don't hesitate to send a message to the sender asking if they really sent the e-mail to you. It’s much easier to check before you open the message than it is to clean viruses off of your computer.
Can I trust every Web site?
Not every Internet neighborhood is safe. Be cautious of a Web site if…
You were referred to the site by e-mail from someone you don’t know.
The site contains objectionable material, such as pornography.
The site makes offers that seem too good to be true. Is it just trying to lure you to the site?
You are asked to provide a credit card number but there is no indication that the Web site ensures its transactions is secure.
The site offers free membership but asks you to provide extensive personal information that does not seem necessary or that you do not want to provide.
More trustworthy sites tend to…
Be certified by an Internet trust organization such as BBBonline, TRUSTe, or WebTrust. Look for their logo on the site and click the logo to make sure it is authentic.
Provide a privacy statement that you can understand and that you are comfortable with.
Provide a way to contact the creator or organization—a physical location, phone number, e-mail address, or mailing address.
Have a clearly posted return policy (when applicable) that allows you to return the merchandise if you are not satisfied.
Offer proof of secure transactions, such as a statement that your credit card information will be encrypted, or a symbol in the browser status area that indicates the transaction is secure.
Is it safe to download that file?
You can help protect your computer by thinking carefully before you download a file.
Heed any warnings. When a Web site attempts to download a file to your computer, Internet Explorer will display a message about saving, running, or installing the file. If the message contains a yellow caution icon, then the file has been identified as a type that could pose a risk.
Make sure the message shows the file source (publisher name). If the publisher can't be identified, it is safer to delete the file unless you know for certain who created it.
Make sure you completely trust the Web site providing the file.
Make sure the file is something you requested or are expecting.
Consider the content. Picture, music, and plain-text files are less likely to be harmful. These file types have names that end with a three-letter extension such as .jpg, .gif, .mp3, or .txt. You should be very cautious with all other file types.