Consider this: Instead of sending out e-newsletters to so many fans, you could set up a blog and tell your fans to go to that. Many authors are already going this way.
Blogs can be started for free through sites like
WordPress. Blogs are supposed to be 2-way communications systems, but don't have to be. You can make entries whenever you want, regularly or on-the-fly, and you don't have to worry about sending out too many and being labeled a "spammer" (a very real possibility if you're trying to email 1500 people). Letting your fans leave comments, and engaging them in teh comments, will make you seem more accessible to them, which usually increases popularity and positively impacts sales.
Many blog services (like WordPress) include RSS feeds, so any entries you make will automatically be sent to those who subscribe. And your blog can be highly personalized, or you can use an easy-to-use template... your choice.