Multipart MIME message from Outlook?

[Kenny]

Hi, I'm trying to send a multipart MIME message from Outlook.

I need to send a HTML email out to clients, but would like
to have another plain text version included for those who
can't see the HTML. I don't want to just let the email
client try to 'strip-out' any text and display that, as
there will not be very much actual text in the HTML
document, mostly images.

It sounds fairly common, but I'm having trouble finding
info on it. It mostly says how to send one format or the
other, not both.

Thanks!