If you're going to send a bulk emails, it will be sent to "spam" folder; and that's bad impression for a business. And sometimes, that email you want to promote will be blocked by gmail, yahoo, etch.
So the best thing to do this will be manually. That will take a lot of time.
1st we have to sort the email to see if there is a duplicates
2nd we need multiple email that you will provide to be used as a sender, if you're using only one email, you will have a potential of being banned.
3rd this is not a one person job. To maximize your potential sales, you need to do it manually, or else you'll be count as a bot