HTML Email for Yahoo

Yahoo is stripping out the tags from HTML to BODY and replacing them with its own pre, tt & big consequently turning my nice HTML email into plain text.

Can anyone tell me why, and what I need to do to stop it doing it please?

I have found that by attaching an html file to the email in yahoo it won't lose its formatting. In other email providers it might lose the formatting though.

...erm, do you mean sending the same file as an attachment?

If it loses it's formatting in other providers, then that's not really acceptable as the vast majority aren't Yahoo users.