Marketers globally rate email marketing as the most powerful online marketing strategy and the one which delivers the best return on investment. Email marketing has a very low cost per acquisition. In other words it is very cheap to acquire and retain customers through emails compared to other marketing channels. There is a reason, your inbox is always full of emails. Email marketing works and it works wonders, provided you know how to deliver your emails in your subscribers' inbox. However the problem is, one in five emails do not reach the inbox. They are either sent to spam folders or are blocked. The percentage of emails that were sent to mailboxes and did not bounce is called the 'Delivery rate'. But Delivery rate does not measure the ability of your email to get into your subscriber's inbox. Therefore, there can be a situation where you have a 99.99 percent delivery rate and still the majority of your emails are ending up in a spam folder and hence not being opened. The percentage of delivered emails that land in a subscriber's inbox is called the 'Inbox placement rate'. You need a high inbox placement rate to get your emails delivered in your subscriber's inbox. In order to improve inbox placement rate, you need to work on improving other KPIs like 'sender score'. There are several KPIs which impact: email deliverability, subscriber engagement and conversions. So if you wish to dramatically reduce your cost per acquisition and increase email marketing ROI, you need to become extremely good at tracking the performance of the various KPIs and metrics used for email marketing. This book focuses solely on the 'analytics' that power your email marketing optimization program. Inside this expert guide, you will discover the various KPIs and metrics used for measuring: email deliverability, subscriber engagement, email conversions and ROI. You will learn about the technology, used by mailbox service providers to make inbox placement decisions.