Why doesn't Microsoft Exchange Intelligent Message Filter (IMF) catch spam that's written in languages other than English?
IMF can catch non-English spam messages, but because the tool is still relatively new, it's more efficient at catching messages written in English. IMF uses Microsoft SmartScreen Technology, which uses feedback from Microsoft Hotmail and MSN users to train itself to recognize spam. Participating users categorize one message per day as being spam or legitimate email. Because most of the messages that users have categorized thus far have been written in English, IMF is weighted toward English messages and does a better job of evaluating English text for spam characteristics than it does evaluating text in other languages. As users begin to report spam messages written in other languages, I expect the tool's multilingual accuracy to improve.
—Paul Robichaux