First you'll need a targeted list.
List:
*You can get it by running paid ads, it comes with a cost and your experience in running ads.
*You can get it by building social media communities (fb, ig, youtube...). You'll need some creativity and time.
*Buying a targeted list, it's time saving and it doesn't cost a lot in comparison to running paid ads (be careful to buy a fresh list)
*Scraping a list, you'll need to create or buy tools.
Cleaning your list:
*If your list it's not an opt-in list, you have to clean it by using tools or subscribe to cleaning services.
Sending email:
*Auto-responders if you have an opt-in list. It's easy to setup (pay and play)
*Use smtp services like elastic emails...you'll need to respect their terms of service.
*Create your own smtp services, you'll need some syslinux skills and basic understanding of how mailing servers work.
*Use tools to send from multiple gmail accounts. You'll need accounts and proxies.
The last step is choosing the right offer, funnels and writing a good content that convert clickers to buyers.
Email marketing is a broad subject, try to be more precise to get accurate answers.
Good luck,