I have to agree with Dennisknows. Aweber is the best email autoresponder in the entire web plus you can earn commisions from referred members
When it comes to email marketing, email delivery is considered an imperative factor. You can make the most out of this service by explaining to customers or subscribers the exact time of sending email. Another significant factor here is to confirm the subscription.
You need look for email marketing tools to help you deliver those email . Email marketing not only can help you blast out email in the short time , you able to track the open rate, the click through rate , the bounce rate , categorize your subscribers and schedule your email to be send. You can look for mailchimp , aweber, ebuzzzz and so on to help you manage and blast your email effectively.
gmail has the best email service that a company can offer. Their software is easy to use and very much user friendly. They respect your privacy too.
Email It is a good option. I strongly recommend that you don't use any desktop based software because you will only end up emailing to your customers junkbox rather than inbox. These guys at Email It use latest authentication methods like SPF, DKIM that will help authenticate your email by big ESPs like Gmail, Hotmail and actually land your email campaign in their inbox. It gives you higher ROI.
Aweber seems to be constantly be mentioned, so I think that settles that. Try contacting your own hosting company, maybe you can get some discount due to being hosted with them at the same time.
Surely the autoresponders are the best tools to deliver lots of emails, build mailing lists etc...all those type of services are paid ones, but here you can get your free autoresponder lifetime NO Cost