Email and spam filtering problem

[#1]

I'm very upset. Yesterday I received an email which was marked as spam but had been originally sent to me on the 28th June. I'm at a loss to know why it was marked as spam when it was a genuine message and why it should suddenly turn up in my inbox over a month late. An explanation would be useful here please.
The reason this has upset me so much is that indirectly, I've lost about £300 in potential rental income on a property I own due to a time waster that I'd have rejected immediately on the strength of what was said in the email.
In the past I turned off the Spam filtering system but found a lot of my messages were bouncing (see http://community.plus.net/forum/index.php/topic,78162.msg639384.html#msg639384) so I had to turn it back on again. I really hate not being in full control of my own email. Please, what can be done?

[#2]

To tell what has happened we'd need to see the full headers from the email as these give details of the date time they went through each server on the way from the sender to you (edit out the email addresses before you post them).

[#3]

For clarification, this email was sent to my domain's email address which, in turn, redirects to my plusnet account. This happens sucessfully most of the time.

Return-path: <++++++++++++++>
Envelope-to: ++++++++++++++++
Delivery-date: Sun, 01 Aug 2010 15:23:24 +0100
Received: from [212.159.7.97] (helo=mx.pcl-ipin01.plus.net)
  by pih-inmx15.plus.net with esmtp (PlusNet MXCore v2.00) id 1OfZRk-0005rV-IA
  for +++++++++++++++; Sun, 01 Aug 2010 15:23:24 +0100
Received-SPF: None identity=pra; client-ip=94.136.40.64;
  receiver=mx.pcl-ipin01.plus.net;
  envelope-from="+++++++++++++";
  x-sender="++++++++++++++++";
  x-conformance=sidf_compatible
Received-SPF: SoftFail identity=mailfrom; client-ip=94.136.40.64;
  receiver=mx.pcl-ipin01.plus.net;
  envelope-from="++++++++++++++";
  x-sender="+++++++++++++";
  x-conformance=sidf_compatible
Received-SPF: None identity=helo; client-ip=94.136.40.64;
  receiver=mx.pcl-ipin01.plus.net;
  envelope-from="+++++++++++";
  x-sender="postmaster@mailex.mailcore.me";
  x-conformance=sidf_compatible
X-SBRS: 4.4
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AkEBANYgVUxeiChAkGdsb2JhbACBd0CXIIY+FQEBAQEJCQwHEQQerW2QBIJoglEEiz0
X-IronPort-AV: E=McAfee;i="5300,2777,6060"; a="380012617"
X-IronPort-AV: E=Sophos;i="4.55,298,1278284400";
  d="scan'208,217";a="380012617"
Received: from mailex.mailcore.me ([94.136.40.64])
  by mx.pcl-ipin01.plus.net with ESMTP; 01 Aug 2010 15:23:15 +0100
Received: from snt0-omc1-s7.snt0.hotmail.com ([65.55.90.18])
by mail10.atlas.pipex.net with esmtp (Exim 4.71)
(envelope-from <++++++++++++>)
id 1OfZRb-00029F-C4
for +++++++++++++; Sun, 01 Aug 2010 15:23:15 +0100
Received: from SNT107-DS5 ([65.55.90.9]) by snt0-omc1-s7.snt0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675);
Sun, 1 Aug 2010 07:23:14 -0700
X-Originating-IP: [82.45.43.91]
X-Originating-Email: [+++++++++++++++]
Message-ID: <SNT107-DS5A4150A6468767B2C709D99AC0@phx.gbl>
From: "ness" <+++++++++++++>
To: <+++++++++++++++>
Date: Mon, 28 Jun 2010 21:50:11 +0100
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0006_01CB170B.E205EF70"
X-Priority: 3
X-MSMail-Priority: Normal
Importance: Normal
X-Mailer: Microsoft Windows Live Mail 14.0.8089.726
X-MimeOLE: Produced By Microsoft MimeOLE V14.0.8089.726
X-OriginalArrivalTime: 01 Aug 2010 14:23:14.0043 (UTC) FILETIME=[13A8C4B0:01CB3185]
X-WebFusion-Spam-Score: 2.1 (++)
X-Spam-Score: 2.1 (++)
X-WebFusion-Spam-Flag: YES
X-Spam-Flag: YES
X-PN-Virus-Filtered: by PlusNet MXCore (v5.00)
X-PN-Spam-Filtered: by PlusNet MXCore (v5.00)
Subject: ****SPAM**** house at leigham
X-Antivirus: avast! (VPS 100801-0, 01/08/2010), Inbound message
X-Antivirus-Status: Clean

[#4]

Quote

Received: from SNT107-DS5 ([65.55.90.9]) by snt0-omc1-s7.snt0.hotmail.com with Microsoft SMTPSVC(6.0.3790.4675);     Sun, 1 Aug 2010 07:23:14 -0700

The email wasn't actually sent until 1st August. I suspect it was sitting in the senders outbox waiting for a send/receive to be done.

[#5]

OK thanks.
I would like to know if the spam filtering system Plusnet uses has atered recently as I've noticed a few emails marked as spam which didn't used to be, eg. advice of my BT bill.
I have Spam filtering enabled because of the problems I had in the past when it was disabled. I have switched off 'discard obvious spam' and tagging spam messages is 'on'. The aggressiveness of the filter is set to 1 and I have chosen the option to move messages identified as spam to my default mailbox. Does this mean that even if the filter picks up any messages it thinks is spam I'll still receive them - in effect, is this as good as disabling spam filtering?

[#6]

No it's not the same as disabling.
With your current settings Plusnet will be discarding absolute blatant spam from known spam sources.
If you turn it off totally your emails go nowhere near the spam checking boxes (Ironport) so prepare for a deluge!

[#7]

This was not marked as spam by Plusnet, but presumably by a server on the sender's side?

Quote

X-WebFusion-Spam-Score: 2.1 (++) X-Spam-Score: 2.1 (++) X-WebFusion-Spam-Flag: YES X-Spam-Flag: YES X-PN-Virus-Filtered: by PlusNet MXCore (v5.00) X-PN-Spam-Filtered: by PlusNet MXCore (v5.00) Subject: ****SPAM**** house at leigham

Messages marked as spam by Plusnet have [-SPAM-] added to the subject line, not ****SPAM****.
There is no sign in the headers that the Ironports either rejected this message or decided to treat it as spam.
HTH
Chris

[#8]

Thanks for pointing that out.
I've contacted my domain's agent, 123-reg, which is part of Webfusion as I'm assuming then that it may have something to do with them.