Trying to understand spam system

Trying to understand spam system


This header is from a mail that made it to my spam folder.  I think it should have been rejected or deleted by the Zoho mail server before it got to waste my life.

Top of mail Header:

Received-SPF: Neutral (zoho.com: 189.112.164.136 is neither permitted nor denied by domain of Rhea.54b0¬stadon.co.uk ) client-ip: 189.112.164.136
Delivered-To: nitation¬gemec.co.uk
Received: from 189-112-164-136.static.ctbctelecom.com.br (189-112-164-136.static.ctbctelecom.com.br [189.112.164.136]) by mx.zohomail.com
    with SMTP id 1422008394179466.76257579495575; Fri, 23 Jan 2015 02:19:54 -0800 (PST)
Return-Path: <Rhea.54b0¬stadon.co.uk>
Date: Fri, 23 Jan 2015 08:19:50 -0200
From: "Charmaine Hancock" <Rhea.54b0¬stadon.co.uk>
Reply-To: "Charmaine Hancock" <Rhea.54b0¬stadon.co.uk>
To: nitation¬gemec.co.uk
Message-ID: <C97F785EF2BB6D8A2E5BC98F4441F6E4-c909ad3fb1b5fa16bb39de798fe0f4f¬gemec.co.uk>

Note in an attempt to defeat email address harvesters I have replaced the @ with ¬ in the above.

Reason to delete 1:  Occurrence in SpamHaus XBL - http://www.spamhaus.org/query/ip/+189.112.164.136
I assume Zoho use connection blocking lists.  If not, why not and when will they?  It would save us all a lot of effort.

Reason to delete 2:


This filter.  It should have deleted the mail not put it in to my spam folder.

So, am I missing something?