Exchange 2010 HTML to Plain Text convertion

We have Exchange 2010 environment and we want all emails to specific subdomain to be delivered to mailbox in Plain Text format and Not HTML or RTF. Exchange 2010 does not support this function so I am looking for a to build a separate Linux box(Ubuntu or CentOS) use fetchmail to download emails and use another tool to convert HTMl/RTF emails to Plain Text and then SMTP back to another email address on exchange.