If you have that many emails, that would be quite the silly way to do this, you shouldn't try to directly send that many emails.
Make sure all the addresses your using are your customers and not some list purchased off the internet, those will just get you in trouble/blocked/blacklisted.
I use something like PHP-List for customers wishing to do this.
There are many ways to use phpList, including operating your own server or getting a free hosted account on phpList.com. See all the ways to get phpList.
www.phplist.org
I usually make a sub domain on the customers site for doing things like this (eg: news.sampledomain.com), and make PHP List the website, so that people can subscribe/unsubscribe. I also rate limit the sending to help not get listed on spam sites. And remove or set reasonably high the maximum messages that can be sent.
And depending on what country your from/sending to there can be certain rules you need to follow.
For heavy customers I put them on their own VPS, in a separate /24 net block I keep just for those customers, and they may need to also pay for mail relay services.
(Those customers have to follow the rules {no spamming, they must already be your customers} we have for them or will be shutdown without notice, and pay additional fees for cleanup.)