bulletproof mailing server needed

We need to promote a website for our client. We mave currently got 20million email addresses and intend to get more, we need a reliable mailing host. We will send out regular mailing and we need to know that you will provide a reliable service including IP addresses that are not banned, if IP becomes banned they need replaceable IP address etc. Our client intially is going to send to bought addresses just so quickly they can establish their own verified optin list. I would like to hear only from experienced suppliers. Maybe you already have an offshore bulletproff mailing server that we could use for our project.