Whitelists Are Not the Solution
The spam epidemic has led to many new innovations -- some good and some bad. In fact, an entire industry has sprung up around spam blocking tools and services. One method receiving quite a bit of attention is whitelisting. Though practically guaranteed to eliminate spam, the cure may be worse than the disease.
A whitelist is a list of people who are allowed to send you e-mail. Those not on your whitelist must prove their identity before you will ever see their message. In most cases, senders simply have to prove that they are indeed human.
Here's how it works. First, someone sends a message to you. The system intercepts the message and checks to see if the sender is on your personal whitelist. If not, then the system quarantines the message and sends back an automated reply to the sender.
The reply instructs the sender to perform one or more tasks that a computer would be unable to do. The tasks can include clicking a link in the automated reply, identifying the subject of a picture, or re-typing a pass phrase. Once the sender has verified that they are human, the system forwards their original message to your e-mail account.
Sounds good, right? It would be impossible for an automated system to go through these steps. It certainly won't be cost effective for a spammer to go through each of these steps for every hapless victim they barrage with spam. After all, they are lucky to get one in ten thousand people to respond to a bulk mailing.
Alas, like most things computer related, it just isn't as good as it sounds. To start off, you're inconveniencing friends and family. This alone isn't usually a big deal as they only have to go through the process once. After they've proven their identity, the system automatically adds them to the whitelist.
However, given that many people have enough difficulty with computers in general and e-mail in particular, complicating the process will certainly stymie one or more people you know. Consequently, though the system seems simple enough to you, you may never receive messages from some people.
More importantly, if you receive e-mail on behalf of your business, the absolute last thing you want to do is throw up a road block between you and your customers. The Internet is supposed to expedite business/customer relations. Don't let your spam problem inconvenience your customers, potential or otherwise. That's just bad business.
There are other potential and unforeseen side effects. For instance, you may be subscribed to several legitimate mailing lists or discussion groups. Often, people who post to such groups will receive the automated reply. For them, this mail is unsolicited. As a result, many people actually block mail from the whitelist services themselves.
Last but not least, not all automated mailings are evil. For instance, our servers routinely e-mail people without human intervention. Such mailings can include Web site statistics reports, form submissions from Web sites, electronic greeting card notifications, forum posts, etc. For all of you online auction junkies, it can also include outbid notices or inquiries from potential bidders.
We're left with the question, "Who would benefit from such a system?" If you have a spam problem and happen to exchange e-mail with a limited number of people, you're a candidate. Better yet, if you use your e-mail account for strictly personal correspondences, then a whitelist e-mail service may be for you.
Otherwise, think twice.