Have you updated your Akismet version to 2,2? For your information an awesome feature is set in the newest version of Akismet 2.2, the feature is Akismet stats. The stat will track comments metrics including missed spam, and false positives: it’s the situation when you say it’s not a spam but Akismet say it’s and display non-spam vs spam count in pie chart. For further information, follow this link:
http://blog.akismet.com/2008/10/20/akismet-221-now-with-stats/
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