This document discusses the continued relevance and importance of email marketing, especially on mobile devices. It notes that email is still the most successful digital marketing activity according to marketers. While email opens on desktops used to dominate, mobile email opens now account for 47% of opens and will reach 60% by late 2014. The document provides tips on optimizing emails for mobile, such as responsive design and considerations like single columns and clear calls-to-action. Though only 18% of emails are currently optimized for mobile, the time is 3pm on Thursdays when most opens and clicks occur, though letting subscribers choose their preferred schedule is also recommended.