I am using Amazon SeS, it offers 62.000 email per month for free, and each extra 1000 for 0.1$, you just need a software that sends the email, I am using mailster for wordpress with SeS.
There is no doubt that amazon ses is a great service but it lacks in tracking deliveries and also a lilttle bit techy for a newbie.i wud preffer getting it from mysmtp dot com coz u can also get guidance from the guys.