The growth of mobile does not just refer to mobile penetration, but as mobile as a hub for all media activity, particular for email. Mobile has nearly eclipsed desktop in terms of email holding 41% of all opens, compared with 36% from last year according to a Knotice report. Despite the initial interaction, mobile does not in fact generate as high engagement with click rates well below desktop. As more senders get savvy about optimizing for mobile, that number is likely to rise.