To send the coupon to your customers, you will need a 3rd party email service like MailChimp.
Take MailChimp as an example; the Email Collection Bar app offers integration with the MailChimp. It will automatically import the email list to your MailChimp account. This automation is a Premium feature. You can find the details on the "Integration" page in the app.
Also, you can export a CSV file of the collected email addresses, and manually import it into the MailChimp. You can find the collected email addresses and the export function on the "Email List" page in the app.
