You will need to do a POST or GET ajax call to a server that has a kind of email sending technology like nodemailer from node.js or php.
First set up a node.js server. Then npm install nodemailer
and configure it to your requirements.
In case you don't have access to a server, you can send emails directly within javascript using a platform like mailgun.com or mailchimp.com. Here is how you would do it with mailgun (that's what I use):
Create an account in mailgun.com, you will get 10.000 emails free each month if you verify your domain else 300.
Learn to use the api here mailgun send email api. First you will have to authenticate, and then you will be able to send emails.
Try it and let me know if you where able to send those emails. Remember that you don't need a server if you use the mailgun API or any other but I recommend you to set up a node.js server with nodemailer for more control.