Mailchimp offers the first 2000 emails free when you create an account, but there is no service that allows you to send millions of emails for free (if someone knows of one, I would LOVE to learn about it, but I don't see how it could exist and be profitable enough to cover hosting).
You would need a very intricate and borderline illegal setup in order to send out that many emails in a way that would be free. Email marketing can get very expensive if you want to do it on a large scale.
I would recommend you to consider a Dedicated server from where you can send many emails rather then looking for free options.
Please search the forums before starting a thread. This question has been asked and answered multiple times, and you could easily have found the answer for yourself. We even have a sticky thread on the subject.
If you later have a specific question to which you've been unable to find and answer, please feel free to post again. Meanwhile, I'm closing this thread.