Vanquish Turns Bayesian Filters Upside Down

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It turns out that Vanquish Labs is literally four miles (6 km) down the road from our offices. So, it was really neat that we could arrange a meeting with Frank Urro, one of the founders of Vanquish Labs of Marlborough MA.

Over coffee and donuts Frank told me about the history of the company and their focus on small business (less than 100 employees), although they have offers for both individuals and medium and large enterprises. Since its formation in 2001, the company has served 12,000 mailboxes and is growing aggressively.

Product-wise - it's a hosted email security service. The core implementation is to point the Internet mail record of the company to their data center. This applies email hygiene processes to the incoming mail. For outbound message coverage, Vanquish users configure their email servers to relay mail to the Vanquish data center. Outbound message control engages the SmartList^TM service which keeps track of all the email addresses sent to, by the user and automatically accepts messages from these folks.

Using the effective, open source ClamAV for anti-virus, the service boasts an optional challenge-response service (called Enhanced Sender Confirmation) and a per-user Bayesian filter algorithm implemented in an unconventional way.

Cool on Treatment of Subject Lines & Website forms

Vanquish has done an interesting thing with the subject line, turning it into a 'Smart Subject^TM' feature. This allows email from any user replying to a message sent by the protected account. So if you send an email to 'customerservice (at) company.com' and it is returned by 'sally.jones (at) company.com, it will not be challenged or held up in the users message queue. Message subject lines are stored for a maximum of 60 days. Of course, this service is designed for non-trivial reply/forwards (blank subject lines aren't stored).

As users visit websites and complete online forms, the domain of the form-submitted site is recorded in the Internet Explorer plugins (FireFox coming) as part of the included SurfMatch^TM service, and messages from that domain are automatically applied to the SmartList. This can reduce the frequency and hassle of user overriding of challenged emails from automated services.

More than adequate for the small business, this service is a great value at  $1.66/month/account. Senders on the SmartList have their messages passed through without intervention.

Even still, the user can automatically remove a sender from their SmartList using the Vanquish Control Panel (left) which is a tiny little link in every message.

Bayesian Filter Upside Down

One special aspect of their implementation is how the Bayesian filter is implemented. Most filtering techniques are trying to use the scoring technique to assess the probability of the message in question as being spam. Vanquish turns that model upside down. Instead, Vanquish assesses the probability that this first time message is a good message, challenging only those that aren't likely to be.

The usually painful training process of the Bayesian filter has been automated too. Every accepted challenge, every received message from an approved sender and every manually overridden challenge is added to the accepted list and used to train the protected users' unique Bayesian dictionary. And, of course, Bayesian Allowed messages are automatically added to the protected users' approved list or removed with a Click of the remove/block buttons of the Control Panel which of course also trains the Bayesian filter.

 Vanquish tries hard to do everything to assure quality inbox content, challenging only when  necessary as determined by the users' preferences and inbox styles.