Vodacom blocks my emails as if I were sending bulk messages. Which I am not.

<p>Vodacom blocks my emails as if I were sending bulk messages. Which I am not. Every time I forward a message which had previously been sent to me by someone, I get this message from Vodacom:</p> <p> </p> <p>-----------------------------------------------------------------------------------------------------------------</p> <p>A message from ********** />to: ********** <p>was considered unsolicited bulk e-mail (UBE).</p> <p>Our internal reference code for your message is 23629-05/Uj69ym42pR1y</p> <p>The message carried your return address, so it was either a genuine mail<br />from you, or a sender address was ****d and your e-mail address abused<br />by third party, in which case we apologize for undesired notification.</p> <p>We do try to minimize backscatter for more prominent cases of UBE and<br />for infected mail, but for less obvious cases some balance between<br />losing genuine mail and sending undesired backscatter is sought,<br />and there can be some collateral damage on either side.</p> <p>First upstream SMTP client IP address: [41.13.36.218] <br />According to a 'Received:' trace, the message apparently originated at:<br /> [41.13.36.218], [192.168.43.93] unknown [41.13.36.218]</p> <p>Return-Path: ********** />From: ****************** ********** />Message-ID: ********** />Subject: Fwd: ******************</p> <p>Delivery of the email was stopped!</p> <p>-----------------------------------------------------------------------------------------------------------------</p> <p> </p> <p>This is unacceptable and a symptom of very poor quality service.</p>