Breakdown of how Microsoft determines the SCL levels
Does anyone know how they determine each level and how often it changes?Thanks
February 10th, 2009 9:08pm

Hi, The spam confidence level (SCL) is the normalized value assigned to a message that indicates, based on the characteristics of a message (such as the content, message header, and so forth), the likelihood that the message is spam. Exchange Server set SCL value for message by using Intelligent Message Filter (Exchange 2003) or Content Filter (Exchange 2007): Intelligent Message Filter is based on patented machine learning technology from Microsoft Research. During its development, Intelligent Message Filter learned distinguishing characteristics of legitimate e-mail messages and unsolicited commercial e-mail (UCE). This learning was based on e-mail messages submitted by Microsoft partners and classified as either legitimate messages or UCE. Based on the characteristics of millions of messages, Intelligent Message Filter recognizes indicators of both legitimate messages and UCE messages. Intelligent Message Filter can accurately assess the probability that an incoming e-mail message is either a legitimate message or UCE. Unlike many other filtering technologies, Intelligent Message Filter uses characteristics from a statistically sound sample of e-mail messages. In addition to UCE, the inclusion of legitimate messages in this sample reduces the chance of mistakes. Because Intelligent Message Filter recognizes characteristics of both legitimate and UCE messages, the accuracy of Intelligent Message Filter is increased. Mike
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February 12th, 2009 12:57pm

Has anyone determined what makes a level 5 versus 6 and so on?Thanks
February 19th, 2009 6:00pm

Hi, Please understand the SCL is determined based on many factors such ascharacteristics of a message, Sender ID filter result and so on. Nevertheless, please understand the code of content filter is secret. We have no method to check why a message is stamped as SCL value 5 or 6.Mike
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March 6th, 2009 8:18am

MikeI have deployed a exchange server 2007 and one of the things that puzzles me is how the SCL is stamped so high on real emails? I got a 9 on one of my emails from my clients the other day. Now of course I can change what I do with rating above 6 , 7 or 8 but what If i need to change the way Exchange Stamps the SCL? is this possible. I have a bunch of clients that always email me, adding them to the trusted domains doesnt mean that the exchange server will always let the emails come through so I need to figure out a better plan. Any suggestions? in the meantime I will read up more about this topic.shivunIT support in hastings
July 9th, 2009 9:14pm

There are a number of things that can make a valid e-mail appear more "spammy". As Mike pointed out, the actual formula is proprietary and you can probably understand why it is not published. If the spammers know the process better, they can bypass it better. Here are some things that can make a message more spammy:1) One line / one sentence messages2) Short messages with no subject3) Messages with only an image4) Content that has "keywords" such as "enhancement" products, naughty words,or cheaply refinancing your house5) Messages whose Sender Id check failedThough I am not sure about this, sometimes even the mention of the word PayPal or eBay can increase the spamminess. At least it seems that way to me.There is usually no single thing that makes a message considered spam, though. It is a combination of a number of factors. Jim McBee - Blog -
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July 9th, 2009 9:39pm

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