This might be a good place to start:
Python Source Walkthrough Series
http://showmedo.com/videos/series?name=qVIxaDJxY
25 karma · joined August 9, 2007
If permission based is OK for your needs, AWeber is top of the line (www.aweber.com)
Here's a similar discussion: http://news.ycombinator.com/item?id=190633