Apple → Strange email formatting in Mail

Every now and then, I will get email messages like this in Mail. If I load it up in a webmail client it looks just fine though, same for Thunderbird. Any idea what's going on?

Headers, as requested.
-snip-
Looks like the message is multipart, but for some reason Mail is displaying the oddly formatted version rather than the text version.

Do you have Mail set to not display images? If so, double-click the message and then Show images. It's a forwarded message as well....maybe that messed with the formatting enough to confuse Mail

There are no images, and it's not a forwarded message.

It's like it's to be viewed in a browser instead of a mail client...
Palm??
I did a google on HTML code and then a subsearch of \par and found a few hits.
Similar code as what you have here but no explanation:
»www.htmlcodetutorial.com ··· 63402664

I can view the plain text version just fine if I go to to View->Message->Plain Text Alternative. I just wish that there was a way for Mail to default to this on these messages.

Lion 10.5

I had a similar problem for a long time. Mail is not parsing the MIME headers correctly, or not choosing the right alternative. After doing some extensive comparisons against a friend's laptop that was not having this problem, it turned out my MIME library was older than his. I grabbed a copy of his, and this cleared up most of the problems. A few days later, Apple released another update, which cleared it up entirely.

Jim