Know-How Exchange : E-Marketing

Looking for recommendations for a good quality, reliable and cost-effective hosted service for email newsletters. Are there any free options that are worthwhile? I've used Topica in the past, but am concerned about their responsiveness.

Basically, we're hoping to grow a list in the beginning and eventually move it to a higher grade paid service like Sparklist, etc. once we build up the membership. For now, just want to test out some concepts and don't want to spend a ton.

Looking for all the usual best practice features (double opt-in, automatic subscribe/unsubscribe, spam free privacy, HTML delivery, bounce handling, etc.). Would appreciate recommendations.

Thanks.