In 2017, an average of 269 billion emails were sent per day. That means the competition for attention in inboxes for email marketers is very high. Email marketing continues to generate high ROI for marketing departments that build a well-thought-out strategy that delivers personalized messages at the right time to the recipients. Below are three types of emails needed in a marketing strategy today: welcome emails, trigger emails and re-engagement emails. All of these emails play a critical role in the customer journey.