David Lemson's WebLog

Product Unit Manager, Exchange


Exchange Intelligent Message Filter announced

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In yesterday evening's keynote at Comdex, Bill Gates announced a new "Intelligent Message Filter" for Exchange Server.  You can read about it over at the hellomate blog.  The press release is also posted on the MS web site.

I wanted to post about this because I am really excited about this capability.  It's roughly the same capability that's been in Outlook 2003 since it was released, but now it works either together with Outlook 2003 or just alone on the server.  It also works together with third party antispam solutions that you might put on the Exchange server, by modifying the same "spam confidence level" or SCL.  There are more technical details on the Exchange web site.  One really nice thing about IMF (and other server-side solutions) is that it works for OWA users as well.  Notice in OWA 2003 that you can manage safe lists through the options page?  That feeds into the decision made based on the SCL set by the IMF or other filters.

Now on to my experience: I've been testing an early pre-release version of the IMF on my personal mail domain.  On that domain, I get around 650 pieces of spam per day.  The cost of having the same address since 1996 and having put that address on many web pages over the years.  I rely on technological solutions to solve my spam problem, and the IMF goes farther than anything ever has.  I directly compared spamassassin on UNIX with the IMF set on a medium setting.  On spamassassin, I even went to the trouble of training the naive bayesian filter with a huge corpus of known good and bad mail, and bumped up the score of 90%+ hits.  The spamassassin rules were updated about once every 2 weeks.

IMF's filter is much more advanced than naive bayesian, don't let anyone tell you "it's just Bayesian" it's not.  And the proof is in the pudding: my experience is that about 3% of spam (20 messages/day) was getting through spamassassin (set so that I wasn't getting any false positives - I had the threshold set at 6).  With IMF (also set so I wasn't getting any false positives), about 0.9% of spam (6 messages/day) is getting through the filter.

To quote from a page mentioned above:

Pricing and Availability

Exchange Intelligent Message Filter will be available in the first half of 2004. Pricing has not been finalized.

[Now Playing: Paul Oakenfold - Dread Rock (04:40)]

  • I for one recommend pricing comparable to Service Pack 1. [Now Playing: Every OS Sucks - Three Dead Trolls in a Baggie]

  • Hi can you e-mail me your setting for IMF. I have an advanced copy of it and I am moving from SpamAssassin. I have SA set at 4.2.. I would like to set IMF's first setting to say 6 for delete and then the setting below that applies to Outlook 2003 clients to 4 or 5 to move to the Junk-Email folder...? What do you think?


    Also when setting up an exchange server to act as a gateway for the exc servers holding the mailboxes... is all I have to do is set it up without mailboxes and designate it as a "front end" server? Just thought you would know..

    -matt chapman

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