mime encoding

[sammall]

I seem to be having a real problem mime encoding mail.
I am using the php mail component to send the mail. This works fine. The email itself is fine in all email clients except Yahoo. For some reason it doesn't seem to work in Yahoo. Or Yahoo doesn't seem to be able to understand the encoding.
I am sending a multipart/alternative email. If I just send an html email, that works fine, but I need it to be multipart/alternative so that it works in non-html email clients. This is what screws Yahoo up.
Can anyone help? I have tried every variation on sending the headers in differnet ways but to no avail. I know this can be done.

[Anon]

I thought about doing it myself too, but then I found the HTML email class at http://www.phpguru.org - way easy to use and worked with every email app I tried (can't remember if I tried Yahoo).