You can use anything that will create HTML, and then send out the page as an attachment from your e-mail client. You just have to make sure that all of the images that you use are on a remote server, and link to them on the server when you create the page. I can use Dreamweaver to do this, GoLive, Freeway, etc. will do this too. If you know HTML, you can also just type out the code in a word processing application that supports HTML export.
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edit: Additionally, to test it, just e-mail it to yourself - it will look like you're sending the file but when you receive it, the html will show up, not just the file.