Considered UNSOLICITED BULK EMAIL, apparently from you - Getting this error!

Hi,
I hoping to get some help on this error from the vodacom3g guy.
I'm receiving this error after trying to attach a signature to my email, going through the vodacom SMTP server.
I'm using Mac and the mail program is thunderbird to attach the signature to the email.
My feeling is that it is getting bounced from the server, although it did go through once out of about 20 attempts trying different formats for the signature.
The signature has been attached in the following formats: jpeg; BMP; png

Some help on resolving this would be greatly appreciated!

The message from the server is as follows:

A message from
to:
to: [email protected]

was considered unsolicited bulk e-mail (UBE).

Our internal reference code for your message is 07434-06/Fowif1eWbZam

The message carried your return address, so it was either a genuine mail
from you, or a sender address was faked and your e-mail address abused
by third party, in which case we apologize for undesired notification.

We do try to minimize backscatter for more prominent cases of UBE and
for infected mail, but for less obvious cases some balance between
losing genuine mail and sending undesired backscatter is sought,
and there can be some collateral damage on either side.

First upstream SMTP client IP address: [41.3.159.211]
According to a 'Received:' trace, the message apparently originated at:
[41.3.159.211], vc-cpt-41-3-159-211.umts.vodacom.co.za unknown
[41.3.159.211]

Return-Path:
From:
Message-ID: <[email protected]>
Subject: another test 23-9-11

Delivery of the email was stopped!


dsn_status

Reporting-MTA: dns; smtp8.vodamail.internal
Received-From-MTA: smtp; vodamail.co.za ([127.0.0.1])
Arrival-Date: Fri, 23 Sep 2011 09:57:32 +0200 (SAST)

Original-Recipient: rfc822;
Final-Recipient: rfc822;
Action: failed
Status: 5.7.0
Diagnostic-Code: smtp; 554 5.7.0 Reject, id=07434-06 - SPAM
Last-Attempt-Date: Fri, 23 Sep 2011 09:57:32 +0200 (SAST)
Final-Log-ID: 07434-06/Fowif1eWbZam

Original-Recipient: rfc822;
Final-Recipient: rfc822;[email protected]
Action: failed
Status: 5.7.0
Diagnostic-Code: smtp; 554 5.7.0 Reject, id=07434-06 - SPAM
Last-Attempt-Date: Fri, 23 Sep 2011 09:57:32 +0200 (SAST)
Final-Log-ID: 07434-06/Fowif1eWbZam


header

Return-Path:
Received: from vc-cpt-41-3-159-211.umts.vodacom.co.za (unknown [41.3.159.211])
by mtafscbe0609smtp8.vodamail.co.za (Postfix) with ESMTP id 94C6B805F3B1;
Fri, 23 Sep 2011 09:57:31 +0200 (SAST)
Message-ID: <[email protected]>
Date: Fri, 23 Sep 2011 09:57:29 +0200
From:
User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7
MIME-Version: 1.0
To:
Subject: another test 23-9-11
Content-Type: multipart/related;
boundary="------------060009070605090500040404"

This is a problem Vodacom has been having with their SMTP (outgoing) mail servers. The technician should be able to sort this out with you. There's nothing you can do from your side unfortunately.

thanks!