Spam – You Don’t’ Have to Suffer.
A look at challenge/response anti-spam systems

I’ve been using DigiPortal’s ChoiceMail challenge/response anti-spam product for several months and it works perfectly. See my reviews of it here
Qurb Inc. another of many anti-spam software vendors announced the general availability of Qurb 3.0 and new features include anti-fraud/anti-phishing protection, anti-spam enhancements and integrated e-mail search. DigiPortal works with any email system, Qurb integrates with Microsoft Outlook or Outlook Express.
Qurb includes an email search engine which appears to be better than the default one built into Outlook. Qurb 3.0 now searches all information in Outlook and Outlook Express to instantly find important e-mail messages, attachments, appointments, contacts, journal entries and other information. Unlike generalized desktop search tools that periodically rescan all files to bring the search index back up-to-date (and which display inaccurate or incomplete results in the interim), Qurb efficiently builds a comprehensive index of the complete contents of Outlook and Outlook Express and keeps the index continuously up-to-date at all times. Qurb claims that this approach conserves computing resources and provides the fastest, most reliable, fully-integrated search capability for Outlook and Outlook Express.
About Challenge/Response Systems
Challenge/response systems blocks all email messages except for those you approve are who you have sent email to. It is VERY feature rich and enables a lot of control over what email can get it by enabling you to create rules. For example, if you want email that contains the subject line, “I Love Coca-Cola” to get to you just create a rule. For all email that ChoiceMail blocks it sends a response to the sender asking them to click on a link to verify that they are a human and not a machine generated spam.
Most spam comes from phony or forged addresses, so the spammer never receives the challenge message. Those that do receive it almost never take the time to respond.
While this methodology is widely understood to be the only way to stop 100% of spam, there has been a perception that it places a large burden on legitimate senders. DigiPortal?s analysis of traffic across servers that process mail for the 90,000 individuals and 300 companies that use its ChoiceMail software demonstrates that this is a fallacy.
The findings show that the average ChoiceMail user receives only two such responses per month. This is because the overwhelming majority of email comes from senders who are already on the user?s list of approved correspondents and are therefore not asked to verify their identity.
?The perception is that people receive email from new correspondents all the time,? said Dr. David Jameson, founder and CTO of DigiPortal. ?Our users are pretty typical, and it turns out that on average they hear from someone they don?t already know about once every two weeks. If everyone used this approach, we could turn off all the other forms of spam protection, the burden of email management would shift from recipients to senders, and senders would spend less than one minute a month to ensure that their legitimate messages get through. That?s a small price to pay to conquer spam once and for all.?
The ChoiceMail identity verification message contains a link to a web page where the sender is asked to enter his or her name and a short message, and then to type in a code that appears on the page in order to prevent spammers from automating the response. Responding to DigiPortal?s challenge message takes 10 to 15 seconds.
If every mailbox in the world were protected by challenge/response system, that would translate into just 30 seconds of reply time per month for the average email user. The result is that spam would simply disappear. Marketers would instead have to turn to opt-in lists consisting of people who have specifically expressed interest in receiving their email solicitations. No other form of spam filtering or email protection would be necessary.
?If challenge/response were universal, the only people who would spend more than a minute or so a month dealing with spam would be people who send an unusual amount of unsolicited mail. That would be completely appropriate,? Jameson said. ?It?s like paying for postage. The sender pays, not the recipient. In this case, you pay with a few seconds of your time instead of with a stamp. And you only pay when you contact someone who doesn?t already know you.?
Filtering by Identity Instead of Content
Instead of using complex rules to spot spam by return address and/or message content, challenge/response systems screen incoming emails primarily on the basis of sender identity. Users create a list of approved senders, usually by importing their existing address book. Messages from individuals on this ?whitelist? are accepted. Senders not on the list receive an automated message asking them to verify their identity. Users can decide which correspondents they trust and add them to their whitelists to ensure that future emails from those senders will be accepted.