My postfix is currently set up to check email content and reject by keywords. However, I can't think of a good way to block this kind of emails:
Return-Path: <gievcyopa@beamtele.com>
Delivered-To: xxx
Received: from beamtele.com (unknown [183.82.3.184])
by XXX (Postfix) with ESMTP id 3FCAACD1FDD
for XXX; Tue, 15 Dec 2015 13:09:36 +0800 (HKT)
From: Jilli M. Gillenwater <gievcyopa@beamtele.com>
To: xxx
Subject: Do you want to have more lovers?
Date: Tue, 15 Dec 2015 10:39:34 +0530
MIME-Version: 1.0
Content-Type: text/html; charset="Windows-1252"
Content-Transfer-Encoding: quoted-printable
Message-Id: <20151215050936.3FCAACD1FDD@xxx>
Good d̞ay my b̻oy .are you availaḃl͒e? I'm realֱly h~rny and want to h00ku֨p t֧onight! s֯en̗d a mٌsg so we can meet!!
M͐y nic̽knͧame is Jilli88 :P
My account is here: http://upqepohh.yoursexychick.ru