Sailthru is the largest sender of personalized email in the world. We send more than 70 billion personalized email messages every year. Email is the most profitable digital marketing channel: it pays for itself in spades, with every $1 spent on email yielding an average $44 return. But email has changed more in the last 5 years than any other form of direct marketing. Leading marketers now view email as part of a complete retention strategy capable of delivering significant revenue, instead of just a standalone channel.