A new junk-mail filter is the best reason to upgrade to the latest version of Microsoft Office

I can think of only one really good reason why the average Microsoft Office user should upgrade to the 2003 version, which goes on sale this week. Fortunately, it's concerning the application most of us spend the most time with each day: Outlook.

The best new feature in Outlook is something you won't see, but which you'll know is there because of something else you won't see. I'm talking about the new Outlook junk-mail filter, which in my informal testing has done an exceptional job of ridding my inbox of spam.

I've been using Outlook 2003 as my default email client, on multiple machines, for more than a month. I like it enough that I've uninstalled the rest of my anti-spam arsenal. That includes third-party applications as well as services, which I found effective but difficult for both sender and recipient to use, not to mention expensive.

When set in "high" blocking mode, the Outlook filter has been something like 95 percent effective in sending spam to my junk-mail folder instead of my inbox. More importantly, the filter is 100 percent effective in blocking pornographic spam containing pictures. Your results may vary, depending on how much mail you get and how much of it is junk. But that's as good a block rate as any spam filter I've seen that doesn't require all senders to register themselves onto a "white list" of authenticated email addresses.

Also, the Microsoft Outlook filter comes with the program and doesn't cost extra. Perhaps the one thing that angers me most about spam is the prospect of paying $50 (£30) or more each year for a filtering service.

Because the spam filtering is built into Outlook, I don't have to install a separate application. In the past, this hasn't been so much a compatibility problem as a bother. But anytime I don't have to install something extra, I consider it a win for system stability.

Microsoft's spam filter doesn't work like most of the standalone products I've seen. While you can add senders to the safe list (which by default already includes your Outlook contact list) and also block addresses that send you spam, the system doesn't attempt to learn from the mail you mark as "spam" and "not spam."

Without getting into the specifics, Microsoft has already looked at millions of spam and non-spam emails and created a filtering mechanism based on some 100,000 variables. This filter is installed as part of Outlook and used to score each incoming message for its spam potential. Cross a certain threshold and the message goes to the spam folder.

Outlook provides two threshold settings: low and high. The default setting is low, which is a good place to run the filter for the first week or two. During this time you will see more spam, but the chances of a false positive trashing a non-spam message are reduced.

While in "low" mode, you can check the spam folder occasionally and add senders who triggered a false positive to your safe senders list. This is especially important for any mailing lists you're on. I was, however, pleasantly surprised that many commercial messages that I actually wanted to receive didn't trigger the spam filter at all.

After a week or two in "low" mode, switch to "high" and you should start seeing the 95 percent or better effectiveness that I've enjoyed. For example, this past Thursday, Outlook sent 264 messages to my junk mail folder. Of those, none were false positives and Outlook allowed only six messages through to my inbox that I considered to be blockable spam. There were also a couple of messages without any content that were apparently being used to verify my email address that also got through.

I've been researching Microsoft's anti-spam technology and will report back next Monday more specifically on how it works and how the company plans to stay ahead of spammers' efforts to defeat it.

Two other aspects of Microsoft's war on spam should be of particular interest to AnchorDesk readers: One is a feature that allows you to add an entire domain to the safe senders list. This matters for newsletters (like ours) that don't appear to come from a single address, but rather from different addresses within a single domain. The new Outlook can accept mail from that domain, so your newsletters get through.

Microsoft has also added a default feature for preventing HTML email from being displayed. Besides preventing porn from showing up in your email, it also keeps people from using server-side HTML images to "spy" on whether you opened the email or not.

This feature, however, also removes graphical elements from newsletters like AnchorDesk, as well as from my daily New York Times, BBC News, and other image-laden emails I want to receive. Adding these senders to the safe senders list, which can be done from within the email or preview pane, allows the images to come through.

Besides the new spam filter, which replaces the ineffective filtering Microsoft had been using for several years, there are other reasons to consider an Outlook upgrade as well:

Taken together, these new features dramatically improve Outlook's usability for people who receive and send a lot of email. If you're one of these people and the spam filter hasn't already sold you on the upgrade, these features should.

Next Monday, I will talk more about Microsoft's war on spam and the role Office plays in it, including more details on how the spam filter actually works. In later columns, I hope to address the other programs in the Office system and what new features have been added to their 2003 versions. And we'll wrap up with a report on my experiences with Microsoft's 2003 version of its Small Business Server, which I really like.

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