I built a newsletter web application but it is going to be far too much work for me to write my own service and host a machine with enough bandwidth to send the newsletters myself.
I would prefer to use an API and have a 3rd party handle the server load. What are the best and cheapest mail sending services that provide an API for my C# code to interface with? I don't need anything fancy. I have a database with users and my application knows what to send and who to send it to. I just need to be able to take that information, drop it on a 3rd party service, and have it begin sending out the emails one by one.
Note: I cannot BCC recipients. Each email is customized for the reader it was sent to.