Sending an HTML email programmatically or through free applications

I am attempting to send an HTML email in Python. I find that email browsers(not sure if thats the correct term) change my html/css especially concerning i开发者_StackOverflow中文版mages. Such as if I have the following CSS:

.myclass { background-image: url(http"//mywebsite.com/images/img1.png }

In Microsoft Outlook, it removes that line of CSS, so...:

.myclass {}

In gmail's browser the layout of my HTML is not shown(its 2 columns) but gmail shows the 2 divs above each other.

I only need to send this email once, its an invitation to an event. And it doesn't need to be done programmatically or just through python.

Do you know of the easiest way to send a html email that contains images(preferably references images on my website & not attached to the email)? Whats the way that has the least headaches? Any open source programs that I can use?

Here is a good tutorial:

http://www.smashingmagazine.com/2010/01/19/design-and-build-an-email-newsletter-without-losing-your-mind/

Hope this helps.