Mailchimp makes it incredibly easy to collect email addresses from your visitors.
The Mailchimp free plan lets you keep up to 2,000 contacts and send 10,000 emails per month, which is more than enough for most website owners. Their plans are very scalable too.
Getting tons of visitors on your website is great, but if you want to engage these users for a an extended period of time, even long after they have visited your site, you need a way to maintain contact with them.
Social media sites come and go but one thing that will likely never change is email. Take advantage of this fact by building an email list with the help of a service such as Mailchimp and rengage with your visitors for years to come.