Proactively ask your customers whether they'd like you to check in on them after their purchase to see if everything works their way. Not only does this allow you to gather email addresses, it also indicates that you care and creates a great touch of 'togetherness'. This is extremely important because it increases trust and the likelihood that a customer comes back which is essential to building and establishing brand loyalty.
Create an automatic email campaign that sends a follow-up email to customers after 3 to 4 weeks.
If you're all about building a strong community, try services like Bonjoro or Soapbox to send a personalised video to your customers.