HTML Email Images

I’ve designed an enewsletter that I want to send a small group. It’s in html, it has absolute paths to the (few) images, I’ve got ALT tags in place, etc. Outlook will send the message fine, and it looks great, but in both webmail and Entourage it ALSO attaches my images files to the email (i.e., they show in the email but then they’re also sent as attachments). How can I fix this?