Thunderbird - prefer text/plain attachment to text/html attachment?

Question

Hi,

Is there a way to have Thunderbird prefer the text/plain attachment to a text/html attachment when both are available in a message?

Here's my problem...

I want to view the output of my cron jobs as plain text. I have Thunderbird configured to use a monospace font for plain text emails. However, somebody (I suspect my Exchange server) is adding a text/html attachment to the message. When Thunderbird sees that it renders the text/html attachment in a proportional font. I'd like Thunderbird to only see the text/plain attachment and render it using monospaced font.

Any ideas?