Yeah, great, I now copy/pasted the whole content of the mail into a Word document, then saved it as HTML file, opened the HTML file in Explorer (it's about 1.3mb including pictures), copy/pasted the whole content of the HTML file back into a new mail message - and voila, the message is 11mb in size again!

Sometimes I just don't get what's happening in the heads of the Microsoft guys when they are developing their software...