By 2023, the number of email users worldwide is expected to grow to 4.3 billion, which is half the world's population. To capitalize on this, consumer brands spend hundreds of thousands of dollars on email marketing. But an email campaign is only successful if the intended audience opens, reads, and interacts with your communication. More often than not, consumers don't even open emails that land outside their inboxes-which is what deliverability is all about.