Making bayesian filter detect some new spam

[Mauricio Tavares]

I have been getting some spam that has not been triggering the
bayesian filter. At least it seems that no matter how many times I
feed them (sa-learn), I still get nothing on bayesian. So, let's take
a look at the header of one of the latest offending emails (the full
email is hiding at http://pastebin.com/S8Hfid2V):

Return-Path: <errores at energysistemonline.com>
Delivered-To: rt at domain.com
Received: from correo.energysistemonline.com
(correo.energysistemonline.com [94.127.190.73])
	by mail.domain.com (Postfix) with ESMTP id 1D50A84402F
	for <support at domain.com>; Tue, 22 Jun 2010 21:46:30 -0400 (EDT)
From: =?iso-8859-1?Q?Beatriz_G=F3mez_Esparza_-_Energy_Sis?=
	=?iso-8859-1?Q?tem?= <beatriz.gomez.esparza at energysistemonline.com>
To: =?iso-8859-1?Q?Canal_de_distribuci?=
	=?iso-8859-1?Q?=F3n?= <support at domain.com>
Subject: =?iso-8859-1?Q?Nuevo_T5850_HDTV_-_Canales_de_televisi=F3n_en_alta_definic?=
	=?iso-8859-1?Q?i=F3n?=
Sender: =?iso-8859-1?Q?Beatriz_G=F3mez_Esparza_-_Energy_Sis?=
	=?iso-8859-1?Q?tem?= <beatriz.gomez.esparza at energysistemonline.com>
Mime-Version: 1.0
Content-Type: text/html; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
Date: Wed, 23 Jun 2010 03:46:28 +0200
Message-ID: <20100623014628zzz.4668292A2AF307E8 at sionemailing>
X-Mailer: ICS SMTP Component V2.53
X-domain-com-MailScanner-Information: Please contact the ISP for more
information
X-domain-com-MailScanner-ID: 1D50A84402F.AFF1A
X-domain-com-MailScanner: Found to be clean
X-domain-com-MailScanner-SpamCheck: not spam, SpamAssassin (not cached,
	score=4.658, required 4.7, BAYES_50 0.00, FUZZY_AMBIEN 2.30,
	HTML_MESSAGE 0.90, MIME_HTML_ONLY 1.46)
X-domain-com-MailScanner-SpamScore: ****
X-domain-com-MailScanner-From: errores at energysistemonline.com
X-Spam-Status: No

As you can see, BAYES completely ignored it. Since this is not the
first time we received an email like this, and I do run sa-learn every
night on the spam folders (I do move these emails to the said
directories), I feel like I must be missing something. Suggestions?