SpamAssassinの日本語対応の改良 https://rio.st/2009/08/05/spamassassin%e3%81%ae%e6%97%a5%e6%9c%ac%e8%aa%9e%e5%af%be%e5%bf%9c%e3%81%ae%e6%94%b9%e8%89%af/