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