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It's a common misconception that the AWL should always contribute a positive adjustment to the score of spam, and a negative one to nonspam. However, that's not the case, and it's not a bug or misconfiguration of SA. In fact, the AWL wouldn't work as well as it does if it didn't assign scores in the "wrong way" sometimes.

Fundamentaly Fundamentally, the AWL is a score averaging system. You can read the "How does It Work" section in AutoWhitelist for a more detailed explanation, but for this now it should be sufficient to know that it works by keeping track of the historical average score for a given sender, and adjusting the score of the message towards their past average.

Now, given that it's an averaging system, it would be impossible for it to always assign negative scores to nonspam messages, unless the pre-awl AWL scores of those messages were always above the average. In the long run, that would only happen if the email scores from that sender were increasing, meaning that the average from that sender was constantly increasing.

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