ClickZ has rounded up some compelling email stats from 2015. Here are a few: Mobile email click-throughs increased 22.8 percent on Black Friday 2015, up from 44.7 percent in 2014. The iPhone is the most popular email client with 32.9 percent of users using the app to check emails. Gmail is second with 15.2 percent market share. Mobile email will account for 15 to 70 percent of email opens.