Send regular newsletters to your customers. Include useful information: new products, promotions (with expiration), product tips, and company news (when appropriate).
Always test to make sure the newsletter is rendered correctly on all email systems (including old Outlook versions).
If you have the resources and the data, you should consider segmenting your users and send multiple versions of the newsletter.

Finding the right frequency and the right content for a newsletter is not always easy. Make sure the newsletter doesn’t land on the customer inbox in the same day as other promotional communication from you.

For more information on how to engage customers with a newsletter check my recent blog post.
Franco Folini lives and works in the eCommerce territory, a wild area between the Kingdom of Technology and the Kingdom of Marketing. He speaks fluently the language of both realms. For many years, Franco has been helping people bridge the divide and successfully collaborate.
If you want to find out more about Franco, visit his LinkedIn profile or send him an email folini[at]gmail.com