I was looking into this a little bit more, and Amazon SES seems incredibly cost effective at $50 for 500,000 e-mails. I'll just have to write some simple code to batch e-mails through the Amazon API, which works on my end because I'm looking for a one-time, no frills e-mail, and don't need all the contact list and management software that goes with it. Also, tracking is easy enough, and I can query my database to find the percentage of users that returned to the site and logged in. Any experiences with Amazon SES?
