Understand the value of a customer’s email address and make every reasonable effort to capture and organize them.
Re-engagement and loyalty are going to become more important than ever as Google becomes more pay-to-play (Facebook’s been there for years, of course).
Email should be the easiest way to gather feedback re-engage your customers, and build loyalty and word-of-mouth. And beyond direct communications, email addresses can be used for retargeting and lookalike audiences on both Facebook and Google ad networks.
Privy is my favorite tool for capturing email addresses on your site, and you should use an Email Service Provider like Mailchimp to segment your lists around interests or other criteria specific to your business.