Article Excerpt: A bit of background: most know Amazon as the world's biggest online store, but years of running one of the largest websites ever has allowed them to create massive, scalable infrastructure that is available for anyone to use. Services like S3 (Simple Storage Service) and EC2 (Elastic Computing Cloud) power a ton of websites.
Simple Email Service works pretty much the same way as the rest of the Amazon infrastructure: use a simple API, pay only for what you use (in this case, how much email you send), grow as you scale. And like most of the rest of the Amazon services, the rates are really, really cheap: only ten cents per thousand emails sent. That's maybe 20% the cost of similar existing services.