SpamAssassin not filtering spam

Hi experts.

I have a redhat server running spamassassin version 2.55 integrated with  MailScanner. I have recently added some new rules to spamassassin, but spam is still arriving. I checked out some of this messages and all of them have a score above the required one (5) but they are getting whitelisted. Here is an Example:

Reply-To: "Jannie Butts" <amuvzatbh@lilli.freeserve.co.uk>
From: "Jannie Butts" <amuvzatbh@lilli.freeserve.co.uk>
To: <jorgep@eurolatina.com.co>
Subject: fill your girlfriend's asshole to the max!
Date: Wed, 28 Jul 2004 02:54:27 -0500
Message-ID: <DXVFBQDBYTVVJJNVWDXCLKKI@msgbox.com>
MIME-Version: 1.0
Content-Type: text/html;
      charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0)
X-Euro-MailScanner-Information: Please contact the ISP for more information
X-Euro-MailScanner: Found to be clean
X-Euro-MailScanner-SpamCheck: not spam (whitelisted),SpamAssassin (score=45.9, required 5, autolearn=spam,BigEvilList_1670 3.00, DISGUISE_VIAGRA 1.00, DRUGS_DEPRESSION 0.10,DRUGS_DEPR_EREC 2.00, DRUGS_DIET 2.00, DRUGS_DIET_EREC 2.00,DRUGS_DIET_PAIN 3.00, DRUGS_ERECTILE 3.00, DRUGS_ERECTILE_OBFU 0.10,DRUGS_MANYKINDS 2.50, DRUGS_PAIN 2.00, DRUGS_PAIN_EREC 2.00,DRUGS_PAIN_OBFU 1.00, FH_FAKE_RCVD_LINE 3.00, HTML_20_30 1.16,HTML_FONT_COLOR_RED 0.10, HTML_MESSAGE 0.10,MIME_HTML_NO_CHARSET 0.76, MIME_HTML_ONLY 0.10, NO_RDNS2 0.01,RATWR19_MESSID 0.41, RCVD_IN_NJABL 0.85, RCVD_IN_ORBS 0.50,RCVD_IN_RFCI 1.45, RM_bw_Generic 0.30, RM_bw_VIAGRA 3.00,SARE_BOUNDARY_07 2.22, SARE_FROM_SPAM_WORD3 0.75,SARE_HTML_NO_BODY3 0.10, SARE_HTML_NO_HTML2 0.10,SARE_HTML_NO_HTML4 0.20, SARE_RECV_IP_061052 1.11,SARE_RECV_IP_FROMIP1 1.67, SARE_RECV_SUSP_1 2.22,SARE_RECV_SUSP_3 1.67, SPECIAL_OFFER 0.30)
X-MailScanner-From: amuvzatbh@lilli.freeserve.co.uk
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441
X-Webmail-Time: Wed, 28 Jul 2004 10:56:27 +0300

As you can see in the X-Euro-MailScanner-SpamCheck header, the score is 45.9 and the required is 5.0.. i thas to clasify this message as Spam but it doesn't.

My question is, why??.. what should i do??.. what is wrong with the configuration??.

Thanks for your help.