After collecting the emails we recommend to use a service like MailChimp, you can use it for free with less of 500 subscribers, and after that you would have to look for the premium packages.
The price structure of this popular e-mail services makes a lot of sense for bloggers to start your own e-mail list.
Remember to create an e-mail list, even if you do not have a unique product. In six months or a year, when you are product is ready would be better to promote it.
The plugins is called WP Email capture, this creates a 2 field form (Name & Email) for capturing emails. Email is double opt in, and allows you to forward opt in to services such as ebooks or software. When you are ready to begin your email marketing campaign, simply export the list into your chosen email marketing software or service.