Win-back: An existing customer is soon approaching the end of his yearly subscription. The customer hasn’t used your product in 3 months and you need a way to win them back and keep them for another year. Create a “win back” email that sends an automated email to all customers that are coming to end of their contract with a list of new product features and a short plan on expected releases in the next six months.
Emails triggered by milestones, like anniversaries and birthdays, are fun to get -- who doesn't like to celebrate a special occasion? The beauty of anniversary emails, in particular, is that they don't require subscribers to input any extra data, and they can work for a variety of senders. Plus, the timeframe can be modified based on the business model.