When a person tells you your email, they are implicitly accepting that you send them information. What you see him to send must be of interest to that person (not just for you). Build a win / win relationship through emails that not only offer your products but also provide useful knowledge, recommendations and advice to the subscriber. If you apply in your lead capture process, you will see that each member of your list is a potential customer.
To properly exploit the power of email marketing it is essential that you have a web domain (even if your site is not developed) and use an email marketing platform.
The domain will help you to have one or more email boxes. It is not recommended that you use your Gmail or Hotmail mail, since you would not enjoy all the benefits that a mailing platform gives you. There are many options in the market, but if you want to start I recommend Mailrelay as program to send mass emails.
In its free plan Mailrelay allows you to manage 15,000 subscribers and make up to 75,000 emails per month. Have you thought about how many sales you can achieve with these figures?