Virus Protection

If your computer connects to the outside world in any way, you need to worry about virus protection. If you use email, share disks (even CDs or DVDs burned by others), or browse the Internet, you're vulnerable to a virus attack. Some viruses are relatively innocuous, only copying some files and maybe changing some minor information on your computer, but most viruses are at least somewhat destructive. Some can completely wipe out your computer right after they send a copy of the virus to everyone you've ever corresponded with.

Although Outlook now has significantly higher levels of virus protection than in previous versions, just because you use Outlook with the object model guard and restriction on programmatic sending of email, it doesn't mean you're safe. One of the most rampant viruses of this past year, the Klez virus, used its own SMTP engine. It didn't trigger the security prompts in Outlook at all. In addition, it spoofed addresses so that no one really knew where the original infection started. Klez searched your hard drive and picked two email addresses at random. The first email address would be marked as the From field in the email it sent, and the second address would be inserted in the To field of the email. If anyone you knew was infected with the Klez virus, you probably received emails from other people accusing you of sending them a virus. There's a good chance it wasn't you. It was Klez pretending to be you.

Klez is just one example of the latest group of insidious viruses in the wild today. If you want to protect yourself from viruses, take a few simple precautions:

• Purchase an antivirus program The best line of defense in the war against viruses is an antivirus program. But it's not good enough to simply install the program; you must make sure that you keep the program current with weekly updates. Most antivirus programs attempt to update their virus definition files once a week, but you can update your virus definitions manually any time you want.

• Be careful with attachments Despite the advances in virus writing, the majority of viruses are still sent in attached files. If you receive an email from someone you don't know with an attached file, do not open that attached file. Instead, send an email to the person asking why he's sending you a file. If he has a legitimate reason for sending you the attachment, he'll usually be very happy to write back and let you know. Even attached files from people you know can contain viruses. As a general rule, I don't open attached files in an email unless I am expecting them. Even then, I usually save them to disk and manually scan them for viruses before I open the file.

• Look at filenames A popular trick these days is to send an attached file with two file extensions, such as joke.jpg.exe. You might think from the name of the file that it's a harmless image, but really, it's an executable file that can do damage to your computer. If you receive a file with two extensions, always contact the person who sent it to you before opening it.

• Keep up to date on new viruses Many companies provide detailed information on their Web site or through email when new viruses come out. By signing up for email alerts from one of these companies, you can find out about new viruses right away. Some of the information usually distributed is potential subject lines, potential attached filenames, and detailed information about how to recover from a virus attack.

Even if you follow all these instructions to the letter, it's still possible you could be the victim of a virus attack. As soon as you know you have a virus, disconnect your computer from the Internet. Find another computer you can use, navigate to the Web site of one of the major antivirus companies, and see whether you can find instructions for cleaning the virus off your computer.

Outlook's Built-In Virus Protection

Outlook offers a number of features that help fight against viruses. The first feature you'll probably run into very quickly is the attachment-blocking feature of Outlook.

After the outbreak of the Melissa and I Love You viruses, Microsoft released a patch for Outlook that prevented certain types of attachments from being opened by double-clicking them. This attachment security has been built into Outlook since Outlook 2002 and remains in Outlook 2003.

Outlook classifies attachments into three different levels:

• Level 1 Attachments included in the Level 1 list aren't accessible within Outlook. If you receive a message with a Level 1 attachment, the InfoBar of the message informs you that Outlook has blocked access to a potentially unsafe attachment. The attachment is still stored with the email message, but you cannot access it.

• Level 2 Level 2 attachments cannot be directly opened within an Outlook email message. You must right-click the attachment and save it to disk before you can open it.

• Level 3 Level 3 attachments are unrestricted attachments. You can double-click to open them directly from within Outlook.

For more information about the specific types of attachments blocked in Outlook 2003, see "Attachment Security," p. 471.

If you're having problems retrieving attachments blocked by Outlook 2003, see "Give Me My Attachments" in the "Troubleshooting" section at the end of this chapter.