Email Newsletter for our website

Dear experts, We require only suggestions/recommendations from experts in Email newsletter handling etc. We are looking to send email newsletters to my website www.SubhaVaastu.com. We tried to send through software, but it requires system should be ON upto completion of the email sending. We are now looking only to have web based software, now our requirement is any body can suggest us which web based software is best to send email newsletter. We have smtp from Amazon SES, our website is a non profit motive vastu shastra information website. Regularly we are updating the site and we would like to send information to our visitors. Also we need to get your suggestion how to auto adding the emails when user put his info for sign for email newsletter etc. For example, now a days [login to view URL] and some other websites also sending quality emails regularly to their visitors, like that we have to send emails regularly to our visitors. We require complete email solutions/recommendations, if any body may right suggested us we will provide them good work on email newsletter. We are looking only Experts in this field.