I spent a day looking for a easy solution to send an embedded HTML by email. I didn't want to use the method suggested in a hint find on this site, because I am always careful not to install too many third-party hacks. I found out that using Netscape 7 it is possible to attach a URL to a message and the HTML page will be embedded in the email.
Now I can just create an HTML page with the images inserted using the complete address (http://...) and upload it on a directory on my website. The email received by my recipients will not contain any attachment, but will display a nice HTML page with images, downloaded directly from my website.
Hope this help someone.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031124180714690