如何阻止Exchange自动将纯文本电子邮件转换为HTML？

I've set up an Exchange 2003 mailbox for emails that will be parsed by my code. The emails are sent as plain text and my code expects to receive them as plain text. However, it appears that Exchange is automatically converting them to HTML. How do I stop it from doing that and just receive the email the way it was sent?I've set up an Exchange 2003 mailbox for emails