This is a useful and simple tutorial to implement Amazon SES Service in your application to send bulk-emails in an efficient way and outside the scope of your website which makes the operation of sending around 600 emails go faster which can help you a lot in building a successful CRM Automated System.
For a full guide, you can find it here :
http://www.codeproject.com/Articles/682681/Implement-Amazon-SES-in-your-ASP-NET-Project