Apple Mail, Google Apps and One User

Question

Every time I receive mail from one user, and only one user, my email POP freezes and will not download any more messages until the message from that user is removed from the server.
There is nothing special about the messages.
We use Google Apps mail and it also happens when I redirect the message to my gmail.com account.
I must force quit apple mail and reopen after the message is gone. It downloads the message but will not download subsequent messages.
It didn't start happening until this summer and every other message I receive behaves normally.
It is very frustrating because the person is a very important client who sends me quite a bit of mail. Any advise? Thank you in advance!

Answer 1

BTW, it also happens when I redirect to non-google mail (rackspace cloud sites). The messages originate from mx1.cbeyond.com if that helps. Here is the full header with email addresses and subjects redacted:
Delivered-To: *@**
Received: by 10.227.141.210 with SMTP id n18cs27159wbu;
Fri, 20 Aug 2010 09:34:02 -0700 (PDT)
Received: by 10.151.68.1 with SMTP id v1mr1889923ybk.383.1282322042071;
Fri, 20 Aug 2010 09:34:02 -0700 (PDT)
Return-Path: <*@**>
Received: from mx.cbeyond.com (mx.cbeyond.com [66.180.96.58])
by mx.google.com with ESMTP id f5si10368850ybi.77.2010.08.20.09.34.01;
Fri, 20 Aug 2010 09:34:01 -0700 (PDT)
Received-SPF: neutral (google.com: 66.180.96.58 is neither permitted nor denied by best guess record for domain of *@**) client-ip=66.180.96.58;
Authentication-Results: mx.google.com; spf=neutral (google.com: 66.180.96.58 is neither permitted nor denied by best guess record for domain of *@**) smtp.mail=*@**
X-IronPort-Anti-Spam-Filtered: true
X-IronPort-Anti-Spam-Result: AnEFABtLbkxCtGAbkWdsb2JhbAB0UJ4xcAEBAQEUEREivDmDB4IwBA
X-IronPort-AV: E=Sophos;i="4.56,239,1280721600";
d="gif'147?png'147,150?scan'147,150,208,217,147,150";a="291048042"
Received: from mx1.cbeyond.com (HELO hub402dal.mmeprod.cbeyond) ([66.180.96.27])
by mx.cbeyond.com with ESMTP; 20 Aug 2010 12:34:01 -0400
Received: from EXEXMBX06.mmeprod.cbeyond ([192.168.13.116]) by
hub402dal.mmeprod.cbeyond ([192.168.13.100]) with mapi; Fri, 20 Aug 2010
12:34:01 -0400
From: *@**
To: *@**
Importance: high
X-Priority: 1
Disposition-Notification-To: *@**
Return-Receipt-To: *@**
Date: Fri, 20 Aug 2010 12:35:18 -0400
Subject:
Thread-Topic:
Thread-Index: ActAeVm08TK68D0QbCdF4RqPfaVAADEz1g
Message-ID: <[email protected]ond>
Accept-Language: en-US
Content-Language: en-US
X-MS-Has-Attach: yes
X-MS-TNEF-Correlator:
acceptlanguage: en-US
Content-Type: multipart/related;
boundary="006_3E80053072CCF24890F5525B6F58ADF7E52772E154EXEXMBX06mmep";
type="multipart/alternative"
MIME-Version: 1.0
--006_3E80053072CCF24890F5525B6F58ADF7E52772E154EXEXMBX06mmep
Content-Type: multipart/alternative;
boundary="000_3E80053072CCF24890F5525B6F58ADF7E52772E154EXEXMBX06mmep"
--000_3E80053072CCF24890F5525B6F58ADF7E52772E154EXEXMBX06mmep
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: quoted-printable